1. Portal. As in, Portal 1.
(because it was free, and turns out my (elderly) PC can just about run it; I've got to what appears to be 2/3rds the way through so far, but as I've just passed the "nnngghh... Fling yourself. Fling into spaaaace" level, I have a feeling GLaDoS might just be lying about how many levels there are, because I'm definitely not on to the faster paced bits which will prove one hell of a challenge on this creaky hardware should they drive the fps any further into single figures. Anyone who spoils it, btw, is going to get a trip through the emancipation field.)
2. Gran Turismo 4. I was weak. I cracked and put the disc back in the machine. Lost half a weekend to pimping up an original Fiat 500 and observing how it squats back on its haunches as if to wheelie if you add a stage 3 turbo, nitrous, supersoft tyres, custom transmission and don't alter the suspension.
3. Flash-based browser Doom. Very nice. Blowing away a few Imps saved me from punching someone in the teeth.
4. Angry Birds (part 1... only! no more! please no more...)
Honourary 5th: FFX