Mining other SHA-256 is becoming useless too. With the the price drop of BTC some people started mining PPC with their ASICs  Network hashrate went up to 4.36 Th/s in the last days, making it harder to earn PPC with GPU only. 

Mining Litecoin is also a bad idea now when you don't have a big cluster of GPUs:

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Thanks a lot

Lot's of reasons that cause the bitcoin to go down at the moment:

1.) In april there was money moved out of cyprus with the help of bitcoins. There was a high demand that caused the price to go up. But this has ended. So less demand and value
2.) Until the end of may the Winklevoss Twins bought lots of Bitcoins for their Bitcoin fund (they claim that they have bought bitcoins for 11 million USD. In april they owned 1% of all existing bitcoins). They probably stopped that which means there is now less demand and lower value.
3.) ASIC Miner is now doing 20% of the hashrate, plus the other ASIC mining people driving the difficulty up a lot. This is the cause that lots of GPU Miners stopped mining bitcoins. But when they don't mine bitcoins anymore, they don't spend them in shops like bitmit or bitcoinpride, they don't place bets or play poker with bitcoins anymore... Which means less demand and lower value too. The ASIC miners seem just to dump their bitcoins to get their investment back or to buy even more ASIC miners.

Hashrate Distribution: http://blockchain.info/pools?timespan=4days
Hashrate goes up: http://blockchain.info/de/charts/hash-rate
Revenues go down: http://blockchain.info/de/charts/miners-revenue
Transaction Value went down: http://blockchain.info/de/charts/estimated-transaction-volume
Number of Transactions went down: http://blockchain.info/de/charts/n-transactions
Number of used Bitcoin Adresses went down: http://blockchain.info/de/charts/n-unique-addresses
Market cap going down: http://blockchain.info/de/charts/market-cap

Sorry, english isn't my native language.
It's no problem as long as the economy is healthy. Usualy a state could make 75% back in taxes of the GDP, and if the state is higher in debt it is no problem. But when the economy is unhealthy (high unemployment, people refuse to buy stuff because of low wages or high interest rates) then it will turn into a problem. The states have to pay back the the goverment bonds including interrest rate, which is another way of a state to gain money. If the economy is down and a state has to pay back old bonds, it will try give out new bonds with a higher interrest rate to attract people to buy those bonds. But when nobody buys those bonds (because of to high inflation or deflation) then the state is in deep shit and will go into bankruptsy. The USA probably won't be affected as the first country, but it is an accepted opinion that this might happen to Japan in 3 to 5 years (If I remember right 380% of GDP is the critical value for Japan). This will affect other states too, as banks are holding japanese goverment bonds and when those aren't paid back they are in trouble. They might go into bankruptsy (probably the state will prevent that by pumping lots of money into them, which is then missing in other places) or at least are not that willing to give out credits to companies anymore, which means to most companies they have to fire their employes, which means that there is more unemployment and a more unhealthy economy. And then the next country is in deep shit... Interrest rates in most countries are already very low to get the people to spend their money (value added tax for the state) instead of making savings.
In such circumstances it is good to have some gold, silver or in modern times cryptocoins that will help you to survive those bad times. And with bad times I mean something like the 1920's when your income from the past days isn't even enough to buy a bread.

http://www.imf.org/external/pubs/ft/fm/2013/01/pdf/fm1301.pdf Page 14

Just have look at the Goverment Dept of some countries:
Japan   245% of GDP
Greece  179% of GDP
Italy     130% of GDP
USA      108% of GDP
Ireland  119% of GDP
Portugal 123% of GDP
Belgium   98% of GDP
Cyprus    92% of GDP
France    92% of GDP
Spain      91% of GDP
UK          93% of GDP
Canada    87% of GDP
Germany  81% of GDP
Hungary  80% of GDP

If there will be a world wide recession, then there is a big chance that those countries will go into bankruptsy. Then the value of Bitcoin and the other cryptocoins will rise a lot. But lets hope this will never happen.

Well, if you are short on money and can only start with one GPU card, then the 115 MHash/s SHA256 / 70 kHash/s scrypt of the APU  is a nice extra. But if you have the money to get 4 7950 that will give 2400 Mhash/s SHA256, then it isn't much extra. Then I would look for a low power CPU instead, because the GPUs pull a lot of power already. APUs are nice when you want to build up a mining rig over a longer time.
For Scrypt you should have the same amount of RAM as your GPU cards, so 4x 3GB = 12 GB. I would say 16 GB should be good as the operation system and the mining software also need a little memory.

OpenCL CPU minining doesn't make much sense for Bitcoin mining. OpenCL isn't optimized for your CPU and there is also a lot of OpenCL platfrom overhead. I've build an optimized pooler cpu miner for my Trinity APU and it gives me about 20 MHash/s running with 4 Threads on my A10-5800K. But running a OpenCL miner like cgminer or bfgminer on the integrated GPU gives about 114 Mhash/s - so it's not worth it if you have any AMD GPU above HD4xxx, or a top range NVIDIA or Intel GPU. For Litecoin CPU mining is still ok, if you have a few computer that you could mine with. For Litecoin mining I get about 30 kHash/s with that optimized cpuminer. Thats's not much, but if you have 3 or 4 simple office PCs, then you can still make some Litecoins with mining on the CPU with an optimized miner.

Well there are some cheap ASICs, Butterfly Labs Jalapeno isn't that expensive. But there is a long waiting list and the difficulty is rising a lot with every shipped ASIC. When you order a Jalapeno now, you will probably get it in a year, and but the bitcoin difficulty will has risen in that time so much that you never will get your investment back (as it takes longer and long to mine a bicoin with a fixed hashrate). So I would say the best would be mining with your equipmet that you have now and keep an eye open for cheap AMD graphic cards that you can add to your mining rig to increase your hashrate without a big investment. 
If you want to mine Bitcoins: Either mine on one of the big pools with lots of hashing power (BTC Guild, 50BTC, Slush's pool) where the rate of solved blocks is high (you will always only get a small piece of the cake, but you will get lots of pieces in a short time) or use a merged mining pool like Bitparking. Those have less haspower, so it could take a lot of hours to solve a block when the pool is unlucky, but you will not only mine Bitcoins, you will also mine other Coins. Namecoins are currently worth $0,32, IXCoin $0,003 and DevCoin $0,00006. That doesn't sound much, but you will easily mine 100 Devcoins in 1 or 2 days and if you collect them over a longer time then this is some little extra money you can make. Or you can balance your mining to more than one pool. That way you can combine both strategies and get a very constant flow from one of the big pools and a not so constant flow from a merged mining pool, but you will also get those altcoins as a nice little extra.

CGMiner and BFGMiner set the Intensity of the main card (thats the one you have connected to a monitor) to a low intensity level so that you still could use it without too much lag. That's usually an intensity of 3 or d (dynamic, where it uses one thread less). If you are just mining with that computer (or don't midn the lag) then rise that card to 9 as well. If you still want to do some stuff (like surfing the web) then try 7 or 8 and see if the lag is acceptable for you.
If you want your child feeling successfull with mining then stay away from Bitcoin and Litecoin, as the difficulty is too high to mine some coins. With your setup you will probably need 45 days for mining one bitcoin (probably even longer as the difficulty is rising a lot because of ASIC miners) and the value is dropping (because of the ASIC miners just dumping their mined coins, and the GPU miners switching to other coins. When the GPU miners move to other coins also the Bitcoin bussiness suffers, so there are less people buying stuff at shops like bitmit or bitcoinpride or bitcoin games like poker or roulette . So there is less demand for bitcoins). Mining Litecoin is easier, you probably will mine a Litecoin within a week. But Litecoins aren't worth much now (<$3). There is a chance that their value will rise when they are traded at Mt.Gox and accepted by more shops. My tip: Mine let him mine some PPCoin. The difficulty is low and with your setup you should be able to mine about 1 PPC per hour. Ok, it's only worth $0.11 per coin, but you will make a lot of coins and there is the chance that its value will rise when shops accept it or Mt.Gox will list it. Another good thing is that it is not only a Proof Of Work coin (getting coins by mining), it is also a Proof Of Stake coin (you get an interrest rate of 1% if you keep your coins for a year). The bad thing is that mined PPCoins needs a lot of confirmations (520 with most pools) which takes about 3 to 4 days before you could move them from the pool to your wallet, but it will teach him to be patient...
Set the  fan to auto (if you don't mind that your card will run a bit hotter) or 85% (if you don't mind the noise). Going over 85% doesn't keep your GPU any cooler than using 85%, but your card will consume more power which could cause stability issues.

You first have to create the configfile. When running CGminer press S then press W. Now you can input the name of the config file, but just press enter. Now you have cgminer.config in the same directory as cgminer.exe.
First thing to adjust is intensity. For SHA256 coins set it to 9, for Scrypt coins you can go higher (usually 12 or 13, depending on your configuration). Then adjust engine clock (as high as possible) and memory clock (for SHA256 as low as possible to save energy, for Scrypt you have to find the sweet spot) where it still runs stable. Probably someone with the same cards can help you with that, or you can do it by trying yourself to find the right values.
One card running hotter than the other could be caused by different things. If you have your cards in a typical pc tower, then usually the lower card heats up the upper card (because hot air moves up). Optimizing the airflow in youir tower should help a bit to cool the upper card down. Another thing is that graphics card companies use cheap and often too much thermal paste. After repasting my ASUS 7950 with Thermaltake TG-3 it now runs 11° C cooler than before.

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Thanks a lot

SirMintALot
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I just got a brand new 7790 for 122 Euro, giving me 260 MHash/s and only pulling 50 Watt.

For Litecoin Mining it is still nice and it's easy to compile.

ARM Cortex A57. 64 bit should give a little boost to Litecoin calculation, and the new extended NEON Engine should have instructions for SHA2 hashing like the VIA Padlock Engine.
AMD said they will bringt 8 core and 16 core CPUs in the second half of 2014.

get some 7790s, it has currently the best price/hashrate ratio and best power consumption/hashrate ratio:
https://suryarpraveen.wordpress.com/2013/04/23/amd-destroys-nvidia-at-bitcoin-mining-can-the-gap-ever-be-bridged/
If you have more money then go for 7950s.

The CPU I would use is an AMD Trinity or Richland APU. They are cheap and they can be used as an extra GPU. The A10-5800K gives about 114 MHash/s for Bitcoin mining, and about 70 kHash/s for Litecoin Mining with a TDP of 120 Watt. The new A10-6700 should be at same level or a bit above, but consumes less power. The A10-6800K should be even better but power consumption should be close to the A10-5800K.

I'm waiting for AMD to bring out their "Seatle" ARM Server CPUs in 2014: 64 bit, 16 cores, > 2GHz, low power consumption ... Ideal for Litecoin Mining 

You mean ASICMiner, Avalon and BFL? I think they try each on their own to make their profit. As the bitcoin is quite stable in the last time I think there isn't anyone manipulating the market yet. But I see the 20% of the networkhashrate of ASICMiner as a big problem. There are pools that have a higher hashrate now, but in a few months when most of the GPU miners will have stopped bitcoin mining and ASICMiner bought even more ASICS, then they might be up to 40%. And from 40% it isn't a long way to 51%...

If they realy would want to merge I think nobody could stop them. But I hope that they are smart enough and know that they would kill the bitcoin with that.

PBKDF2-HMAC-SHA512 / AES: 95 kHash/s
PBKDF2-HMAC-RipeMD160 boot-mode / AES: 451 kHash/s

OK, RipeMD took 40 seconds, SHA512 is 5 times slower, so it will take 10 minutes. Let's guess it was a simple password, it would take much longer with a better SHA512 password. But then remember it was just two HD6990. Let's see what we can do with a Cluster of 25 Titans: 25 x 163.0 kH/s = 4075 kHash/s. Or with a cluster of 25 HD7970: 25 x 233.0 kH/s = 5825 kHash/s.

You also have to take into consideration that you don't have to find the exact passphrase for pasword cracking, you just have to find a combination of symbols that gives you the exact same hash. d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592 is the SHA256 hash of "The quick brown fox jumps over the lazy dog". So "a!kL07gS1" might give you the same hash (it is just an example, it doesn't have the same hash) and you could decrypt the file with that as well. So what can you do for more security is either using a hashfunktion that generates a longer hash (07e547d9586f6a73f73fbac0435ed76951218fb7d0c8d788a309d785436bbb642e93a252a954f23 912547d1e8a3b5ed6e1bfd7097821233fa0538f3db854fee6 is the SHA512 hash of "The quick brown fox jumps over the lazy dog") or using an slow algorythm like blowfish. But with more hashing power the time needed to solve even those puzzles gets shorter. Just imagine what you could do with the 138 Thash/s SHA256 hashpower that the bitcoin network currently has LOL. Sure not much people here would have the money to build a cluster of 200 Titan, HD7970 or Xeon Phi just to crack some passwords, but it's no problem for the secret services (Do I hear Prism or GCHQ? ) or some criminal organisations to do this.