Blockchains are insanely expensive to secure. It is not clear that proof of stake really works to secure a chain, there still seem to be claims floating about that they cannot actually operate without proof of work mining, plus they all seem to be nastily similar to "solidcoin" in having centralised trusted servers that get to make up checkpoints thus maybe could easily attack the coin since they get to make up the checkpoints as they go.
So maybe the eight merged mined coins are kind of special: bitcoin, namecoin, devcoin, groupcoin, ixcoin, i0coin, coiledcoin and geistgeld.
Out of those, coiledcoin and geistgeld are still very much under the radar.
In fact the geistgeld experiment, which is, to test just how fast you can have the blocks without screwing up all the other coins in the merge, maybe has still not really been seriously done: so few people include geistgeld in their merge, and its difficulty adjusts so incredibly fast, that I don't think enough mining power has even been sent at it yet to really determine for sure whether it really is just too darn fast. Possibly it might even need to have its block speed slowed a little, or maybe it just needs more merged mining pool and miners who merged mine to include it in their merges?
Since the vast majority of scrypt based coins, along with the vast majority of SHA256 coins that are not merged mined, will probably eventually crumble under the fact that they simply cannot muster enough mining power to secure their blockchains, these eight merged mined coins continue to seem to me to be some of the likeliest contenders going forward, so it seems to me if you want to get involved in the support side on coins - maintaining the code - coiledcoin and geistgeld could be among the most profitable options available, since you can still mine them so easily.
Groupcoin is also very interesting too even though it is merged by mmpool.bitparking.com because although lots of people probably have some (any miner at mmpool that bothered to tell mmpool a groupcoin address, for example) I do not know of any website-type exchange (as distinct from Open Transactions servers, for example) that support groupcoin yet, so all the "most profitable coin" sites fail to mention groupcoin, so maybe you might still be able to pick them up cheap from people who get them but have not yet realised their potential.
So groupcoin would be another good one to work on.
Basically all the merged mined coins need the code fixes, or kind of code fixes, that were done for I0Coin, so make up for the fact that the original implementation of merged mining turns out to be a massive hog of RAM as chains grow larger. Of those, coiledcoin and geistgeld retain so far the greatest potential for picking up lots of coins at low difficulty before other merged miners realise how much they are missing out on by failing to include them in their merge but groupcoin, having been included in at least one major merged mining pool's merge but not, as far as I am aware, having being picked up by any website-style exchanges yet, also has possibly good potential for picking up cheap since people are probably mining it (look at its difficulty!) but maybe don't know what it is worth. (If you can find anyone willing to sell any for the prices shown at
http://galaxies.mygamesonline.org/latestrates.inc you are probably lucky and should take them up on it...)
Tenebrix and Fairbrix are interesting due to being so incredibly low difficulty, but they are scrypt coins so are probably doomed... but hey, the idiots buying all the other scrypt coins might not realise that most scrypt coins are doomed so hey, given how insanely low difficulty they are why the heck not pick up a few tens or hundreds of thousands of each just in case? Afterall, even just recently people were buying BBQcoins that you could pick up with just a single CPU core for a year or so, who knows, maybe they will also pay fortunes for other insanely easy to mine scrypt based coins?
-MarkM-
