Mohtalim

http://www.bitcoin.org/

Cryptocurrency. Also an actual GPGPU application, although it does relatively useless work. (Just calculating valid SHA hashes until one is found that meets an arbitrary fitness function.)

http://www.quora.com/Is-the-cryptocurre ... am-Cohen-2
http://www.reddit.com/r/NonAustrianEcon ... ea/c1xd0v9

Would be nice if it actually calculated something useful, like primes or dna folding or something like that.

Yes, it certainly would be. That's a lot of electricity.