It probably makes him nervous because exponential growth might imply an exponential slide.

There is a commons issue, but it's not a 'Tragedy of the Commons' for several reasons repeatedly pointed out to yourself.  In the case of Wal-Mart and it's competitors, or any other large retailer and it's direct competitors, Wal-mart does benefit from the generic security of the blockchain that it's competitors contribute to, and vice versa; but what motivates Wal-Mart to contribute directly (by running or sponsoring mining clients themselves) or indirectly (by paying transactions fees to motivate third party miners) because Wal-Mart's competitors can ignore Wal-Mart's transactions whether they are fee paying or not.  Wal-Mart can do the same to it's competitors.  Granted, it wouldn't be easy to isolate the transactions produced by Wal-Mart's competitors from those of the network at-large, but if anyone has the ability to do it, Wal-Mart does.  I can think of a number of ways that a competitor's addresses could be automaticly identified, with varying degrees of success.  Even if this were not possible, if Wal-Mart is running their own miners then they can simply ignore any transaction below a certain fee and still have an economic incentive to run miners in order to process their own transactions for free.  Wal-Mart's competitors have the same incentives.

This is not a 'cartel' problem because Wal-MArt isn't a cartel itself, and the fees that they would charge others for transactions would exist primarily to hamper the successes of it's competitors, not collude to increase the price.  Independent miners would still be able to set their transactions fees lower than Wal-Mart, collecting all the transaction fees that Wal-Mart and it's competitors forgo, but this would not really undercut Wal-MArt because they are not in the game for direct profit but to defend their business model.  Wal-Mart alone has enough transactions per second to justify running some major miners just to process their own transactions; all others aside.

And they are just an example of how this would work.  This is an example of any market player who has an outsized interest in the system, there are many others that would have similar motivations to process transactions beyond direct profit.  Another such example is the "Bitcoin Bank", which has a motivation to sponsor miners, directly or indirectly, in the same fashion that present banks have the motivation to spend a million dollars on a bank safe.  In the case of a bank, however, direct profit is also a motivation.

This is one of those classic questions that regulars get tired of answering.

The Bitcoin network can scale significantly, the 1 meg hard limit is only there to halt 'transaction spam' if an error in the code is found and exploited.  That limit can be raised or removed as the userbase may deem necessary.  Even if it can't, much of the future transactions will still be off-network, like the transactions that occur between MyBitcoin accounts are at present.

Exactly.  And this is why I brought up Wal-Mart and it's competitors.  If Wal-mart accepts Bitcoin, it has a strong incentive to directly participate in the security of the network.  And then so does all it's competitors.  And the reverse is also generally true.  The mom&pop  vendors may not feel motivated to participate in the mining directly, but they are going to want to see their transactions processed in a timely manner as well.

I didn't do it.  Is it still a compliment?

It's not a contradiction, at least one of your premises is wrong.  Namely, that the size of an attacker can be known in advance.  It cannot.  But the proof-of-work system exists to make a brute force blockchain attack to be as expensive for the attacker as the network as a whole can afford.  What the total network can afford is always changing with the size and overall bitcoin wealth of the Bitcoin economy & userbase.  The beauty of the current system is that it associates a personal need of certain particular users to the collective need of the userbase.  Namely the personal need of well-heeled users to rapidly confirm large and/or high risk transactions with the collective need of the userbase to maintain as high a level of blockchain security as is reasonablely possible.  Your assumptions are that the current protocol cannot maintain the level of security.  I assert that you have failed to show this in any fashion.  Show me how you might guess the level of a future attacker, and I might be willing to entertain flights-of-fancy; but thus far this has all been about how you would have done things differently.  Feel free to go do it.  I'm sure others will try it.  Hell, I might even try it.  But based on what you have written thus far, you still don't really grok what Bitcoin is actually doing to protect itself.  There is more to it than you have expressed, and the smaller rules have an interlocking interplay with the major part of the protocol that actually makes the task of attacking, DOSing or spoofing the network so much more difficult to achieve in practice than it is written into the white paper as a matter of theory.  One such rule is the blockchain release benchmark.  With each new release, the new client contains a list of particular blocks whose confirmed hash number is recorded in a hard coded list in the source.  At present, that list is the same for each client because they are pretty much all the same client.  In the future, the benchmarks would be different for each independently maintained client.  The reason for this list is to protect the history of the blockchain from a successful brute force attack of the blockchain, because in order for an attacker to rewrite the history of the blockchain before the newest benchmarked block, the attacker would have to produce a forged block, that could pass the validity tests, that still had the same hash as the original benchmarked block.  In order for an attacker to continue to succeed, he would have to keep doing this for every benchmarked block in the list; because it's not something that can be changed in the running nodes.  This problem is compounded further if, in the future, alternative Bitcoin clients use an alternative list of benchmarked nodes; as the attacker would have to either do this magic with all the benchmarked blocks in all the alternative clients as well.  The mathmatical difficulty of doing this is probably quantifiable by some of the math geeks on this forum, but my back of the envelope numbers tell me that the odds of being able to do this is so astronomically against the attacker and in favor of the network that, (even ignoring all of the other problems with it such as the near impossible task of just getting back that far with the current ability of the network) the attack would be so many orders of magnitude higher difficulty than the simple single block rewrite that the cost of building such a supercomputer would likely exceed the total wealth of the top 20 wealthiest nations on the planet, and perhaps the entire wealth of the planet itself.  Which, of course, effectively makes such a thing a literal impossibility unless there is some alien race that arrives on Earth in the next 120 years bent on the task of breaking Bitcoin.

And that is just one of the checks beyond the protocol itself that exists within the Bitcoin client.

There is more than one way to look at that, but if one is restricting oneself to the mass weight of each in an "above ground" (i.e. already mined) and elemental (i.e. refined to an elemental metal) and in a quantifiable form (mostly means it's in bullion or coined form) then there is much more gold in our modern world than silver.  The reason for this is that there are many industrial and commercial uses for silver beyond it's use as a store of value.  Such as, up until the relatively recent takeover of digital photography, silver was a necessary component of photo development chemicals, some trivial amount of which always ended up permanently in the photographs themselves.  Silver also has excellent electrical properties, and is therefore the ideal conductor for mission critical devices that weight is a severe limitation; such as spacecraft, satellites and high-altitude military aircraft.  Silver also has well documented antibacterial properties in it's elemental form, and for this reason is the traditional material that the food implements used by the wealthy.  In today's world, that use isn't as significant, but many surgical materials still contain silver in non-trivial amounts.

All of these uses, and others less significant, tend to 'consume' elemental silver; unlike it's use in jewelry or as a store of value.  On the other hand, gold has relatively few industrial uses that cannot be met by other means.  For example, gold does not corrode, so a gold plated steel hulled ship would be largely immune from saltwater corrosion; but zinc corrodes in a manner that actually protects steel (it's an electro-chemical thing that I don't understand, but I know that zinc used in this fashion is called a "sacrificial anode").  The zinc needs to be replaced periodicly, but over the expected lifetime of such a ship, zinc is by far the better deal.

So, the result of over a century of the industrial age, almost all of the gold ever mined is still known to exist, more or less.  Whereas much of the silver mined, although it's 16 times more abundant in the Earth's crust than gold, no longer exists in any economicly recoverable fashion.

No.

Usually it means "away", as in 'Go forth, young man."

You, Sir, are a walking self-contradiction.

Yes, it can.  Confirmations are exactly what they appear to be, confirmations.  Specificly they are confirmations that this is the one-true-transaction that will ever be.  They are not confirmations that the transaction is valid, nor are they confirmations that the person in the drive through was the true owner of those coins just a moment ago.  Those things can be verified by the McD's own client by scanning the relevant blocks and the transactions waiting in it's own queue.  The double spend attack is technically difficult, and made more difficult by the fact that vendors such as McD's have a strong vested interest in making certain that, not only is their blockchain accurate to the moment, but they also are looking for opposing transactions in the mining queue.  If they don't see such a transaction (or are not notified that one exists by a contracted agency) by the time you make it up to the window, it's very unlikely that any other transaction would be able to trump their transaction even if you had attempted a double spend.  That is, so long as the Internet connection for the McD's wasn't down.  And if you had the skills to do this to McD's, would you go to all that trouble over a free lunch?  Not likely.  Bitcoin banks will exist, but they will not be necessary for the vast majority of small retail transactions.

No, it does not mean that.  The most profitable attack that anyone could perform on the bitcoin network if they controlled more hashing power than the entire remainder of the network would be to reclaim coins that they recently owned and spent.  They could not take coins that they never owned, not even from the most recent block.  Nor could they make bitcoins beyond the parameters of the system, legitimately or not.

And this attack, as difficult as it is, only lets the attacker respend his most recently spent coins because it allows an attacker to rewrite the most recent block.  However, the difficulty for the attacker goes up dramaticly the farther back in the blockchain the transactions that he wishes to overwrite might reside.  Otherwise the honest network will continue to outpace his total-proof-of-work, based upon how far back he must go to get at said transactions.

I want one.

peg the bitcoin price to the 24 hour weighted average from MtGox, and have a script update the price once each night.

Diving into my wireless router, I find that there are options built into it for a 'captive portal' like one would encounter in a public hotspot.  Wifidog seems to be able to supply my needs fine, with just a splash clickthrough screen and copious logging and stats.  However, it seems to require an outside server for the spash and clickthrough portion.  Does anyone know of a cheap/free solution for this?  I want users to see the disclaimer, references to the EFF open wireless movement, and notice of logging of activities.  I do have a linux machine on the same intranet, using the same router but wired, so that might be a solution.

I don't know about all that.  What about the online system for PapaJohn's pizzia?  I'm sure that their online ordering system uses some kind of API that could be connected to, if they will let you, which is a big if.

Yes, the initial hash-checking of the blockchain is also building a local database file that your client uses in the future to quickly find older transactions.  This takes massive amounts of disk I/O.  It would be better to bootstrap onto a regular hard disk and then copy the resulting database file and wallet.dat file to a new instance on a flash drive if you are looking to make it portable.  Ongoing updates are not as bad, but could still take a while over USB.

this is a local arrangement, but I have seen it done.

The client downloads the old blockchain in sets of 500 blocks each, and then proceeds to hash-check everything in each of those blocks before proceeding to the next set.  So it's not neccessarily the speed of your Internet connection that is the limiting factor.  Are you using an old machine?

If gold or bitcoins become the next international reserve currency, you will likely know roughly how much purchasing power 6830 ounces of gold or 6830 bitcoins would have.  Because you would be conditioned to think of value in reference to gold or bitcoins, as you have be conditioned to think of value in reference to the national fiat currencies.