To answer the original question, it's really quite easy.  Take your favourite server package (I like twistd and nevow for speed and security, but the learning curve can be kind of steep.)  Create an index page that pulls the list of files from the database/filesystem/wherever-you're-choosing-to-store-them and generates download links.  Each download link should contain a nonce sized to make it extremely difficult for someone else to intercept a paid-for download and snag a copy themselves.  Download link goes to a page which uses the nonce as an ID number and provides a bitcoin address to which payment may be sent.  Upon receipt of payment, page unlocks and provides file for download. 


If you want a plain-Jane, looks-ugly-but-works standalone server application that functions as described above, I could be convinced to put one together for you for a couple of bitcoins.

When and if you get your coins back, the first thing to do with the new wallet file is to run the client with the parameter -keypool=10000.  This will change the number of pre-generated addresses from the pitifully small 100 that it is by default, to a large enough quantity that your backup copy should be good for at least a year or two.  10k addresses puts the wallet size at about 70Mb, which is large, but not unbearably so, and the inconvenience is far less than that of losing coins.  It may take a half hour or so to generate them, depending on how fast your machine is, but after that it will run as normal.

Strictly speaking it generates a new key any time the number of keys in the pool drops below the number it thinks it should have.  The default is 100, but you can adjust that with the -keypool parameter.  Personally I run it once with the keypool size set to 10,000, and then backup the wallet.  It makes your wallet about 70Mb, but you don't have to worry about the backup becoming obsolete for quite a while.  Key creations and the size of the pool are recorded in the debug.log file if you feel the need to check on its status.

Scroll to either the top or the bottom of the thread page.  You will see a link that says, "notify".  Click it to turn notifications on or off.

The sensible thing to do in that case would be to keep two different wallet files, one for personal, and one for business.  You can use the -datadir parameter for the client to point it at a different folder for storing one or the other.  It takes a bit more disk space, but that's relatively cheap these days, and it's a lot less hassle than trying to keep it all separate manually.

I haven't looked at the details of how your code works, so I can't be sure, but there is a possibility that you could save yourself some maintenance effort on it if you put it together as a magicrescue recipe...  Magicrescue scans block devices looking for particular sigils to recover certain kinds of files, and then calls arbitrary scripts to extract them.  I don't know if it would make anything easier or not, but it might be worth a look.

Edit:  Also, This seems donation-worthy, but I'm not seeing an address listed...

Anyone else who wants to see this made can post their offer here and I'll keep the bounties page up to date.

I have a client here in Spokane, Washington that would like to be able to use GPG with Outlook 2010.  So far as I can find, none of the existing Outlook plugins function with the new version, and I have been unable to find anyone who is working on a new one.  (My guess is that most of the people who use GPG don't use Outlook as, security-wise, that's kind of like trying to fix a leaky dam with a new coat of paint...)

Criteria:

1)  Must function on 32 and 64 bit versions of Windows from XP through 7, with 32 or 64 bit versions of Outlook 2010.  (Compile-time options for different combinations of system count as functional)

2)  Must be capable of encrypting, decrypting, signing, and verifying emails and attachments.

3)  An interface to manager keys (upload and download keys from keyservers, create, sign, delete, etc.) is not strictly necessary, but if it has one that is reasonably easy for a non-technical user to use, I will offer a percentage of any fees I charge to my clients for installing this software in addition to the compensation offered below.

4)  Must be licensable as free, open-source software.  I prefer GPL, but anything that allows for free distribution, modification, and use (including commercial use) is acceptable.  If you wish to use one of the licenses that requires the original author's information to remain attached to the program while still allowing redistribution and modification, that's fine by me.


Compensation:

I am offering the contents of http://blockexplorer.com/address/1NHiyS852dzsAYcrwdis2C5L9rSQ9YLJye for delivery of a completed program with source code that meets the criteria above.  It is starting at 10BTC, but other people who have need of this software are welcome to contribute.  This offer will remain open for a period of one year from date of posting.  If it has not been claimed by then, I will return all contributions to the address from whence they came, according to block explorer.  If it becomes necessary to cancel this offer for any other reason, I will return all contributions to the address from whence they came according to block explorer.  (So don't throw away your empty wallet)


Since I do have someone who wants this, it may be possible to haggle.  Feel free to PM me if you have any questions or counter-offers.

Personally I'd rather have a capture on every post or something to slow down the spam.  I've been here since the 29th of April, and have 8 posts, but since I don't lurk here all day, every day, I don't have enough hours.  Which is a pity since I have a bounty to post in the marketplace.  

No reason I can't just sit here and play Angry Birds for an hour and a half, but there's got to be a better way to do this.

What I mean is that Explorer goes to extra effort to keep you out of the Application Data directory as compared to other ones, even normal hidden ones.  Simply telling it to show hidden files, at least in my experience, is not enough to make it show up.  Nor will it auto-complete the path name for you if you start to type it.  I hadn't thought of doing the %appdata% thing though.  But then I don't tend to fight with the Windows GUI much since I started out with MS-DOS, and am usually faster in the terminal anyway.     (Especially where tab completion of the directory name works on the Application Data directory.    )

Ah.  There *is* a new version.  My eyes must have been playing tricks on me. 

If it makes you feel better, the open-source, P2P nature of Bitcoin makes it so close to impossible for the system as a whole to be a scam that the odds aren't even worth calculating.  There isn't any centralised authority that can be skimming money and planning to ditch the people who bought into it and leave them with nothing.  It will exist for as long as there are people willing to let their computers process transactions, and they will be worth whatever people are willing to trade for them.

About the only thing you have to worry about is that they may currently be over-valued.  Which really isn't any worse than any other currency or commodity.  The US Dollar, and gold currently being two, prominent examples. 

Of course, as with any currency, there will be scammers who use it.  So be as cautious about choosing who you do business with in Bitcoins as you would be about who you do business with in cash.

I'm looking at the value of 1 BTC heading toward $3, and wondering if it might not be prudent to expand the number of decimal places accessible to the standard client to three.  It's likely easier to convince people to use Bitcoins when the actual cost of the product they are buying won't be subject to multiple cents worth of rounding.  Unless, of course, most merchants are planning to round down...

The important part of your bitcoin client is the wallet.dat file.    Make a backup of that file regularly.  (Or, at least, every time you generate a new address.)  It should be in the $HOME$\Application Data\Bitcoin directory on XP.  I forget where it is on Vista and later.  It's similar, but the directories are locked out through the file browser, not just hidden, so you'll have to use a command prompt to get to it.

Once you've done that, uninstall the program, and then wipe out the entire contents of the directory.  You've probably got a corrupted file somehow.  You'll have to redownload the entire block chain, but that shouldn't be too big a deal.  Once you've done that, reinstall, and copy your backed-up wallet.dat back into the settings directory.

If you need help doing any of that, let me know.  I help people with software faults like this all the time.

(I'm afraid I can't help much with the mybitcoin people.  Never used them, never will.)

The simple counter to the "Bitcoins are being used for illegal activities and should be banned" argument is that, since bitcoins have a transaction record easily available on the public net, without even needing a search warrant or anything, bitcoins are actually *more* traceable than cash.  You don't need to set someone up with marked bills.  *Every* bill is marked.  When the politicians finally get around to trumpeting about how it's a haven for criminals, be sure to point that out.  It's no worse than bank transfers between numbered accounts, and it's considerably easier for law enforcement to follow any trail that gets left behind.

I'm afraid I'm just getting started and only have a few bitcents to my name, but I can offer a bit of practical advice.  Instead of all bottled water, go to the local camping supplies store, and buy some water filters and pumps.  Used carefully, they can provide 400 gallons of water for less than the cost of one case of bottles.  All you need are a few mud puddles. (A cotton sock for a pre-filter will extend the life considerably.)

You can already sell "freshly minted" coins for a premium.  There aren't a lot of buyers, but there are a few.

There are also a number of sites popping up to take your coins and mix them around with other people's coins so that they can't be followed back to you.

The thing to watch out for is some politician trying to ban the currency because it's used for illegal activities.  The real reason will be because they can't control it, but stopping drug dealers and money launderers, and (most especially) tax evaders is the reason that they'll give.