Nothing to play on the PC for me. I've been tinkering with Penumbra though. There are no good single player games I haven't beaten. And multiplayer usually gets boring really quickly. The last multiplayer I've enjoyed a lot was Call of Duty 1, and even then it was too easy.
I've been filling my time with an Xbox360. Played the excellent Perfect Dark Zero and now I'm play Halo 2. I don't think I'm gonna upgrade my hardware so soon, since I'm having too much fun with the 360 and there are a lot more games to play there than on the PC. But, I'm still waiting for Duke Nukem Forever. If that ever releases, I might just buy a new PC just to play it.