Currently, WCG doesn't have any active projects that use GPU for crunching - apparently, there's been talk/even possible development, but nothing concrete just yet. As far as I know, the techs are incredibly bogged down by a very long list of items that they've got on their plate (launching new projects being pretty high on the list), and so, I'm sure that GPU processing will come soon, but don't hold your breath for it...

As to other non-WCG projects that can make use of your GPU, I'd suggest having a look in the I want to do GPU research for starters... (if you do a search in the forum for the word "GPU", you'll find loads of threads that refer to this particular subject.