I downloaded the inFamous demo over the weekend, thanks to the early demo code I got with my preorder at Best Buy, and I've been playing that quite a bit - I've already beaten it three times, but it calls to me... it's rather addicting (honestly, it's the best demo I've played on the PS3 since LittleBigPlanet).
I also booted up my old SNES emulator last night for some odd reason and started playing Zombies Ate My Neighbors - haven't played that in YEARS!