The Darkness looks cool, not the best-looking game ever but seems to have a nice atmospere and fun gameplay. I hope they manage to squeeze a good story into it as well.
Granted, I've barely played a Pokemon game in my life, but man...those battles looked really simple, slow and boring. I have this thing against RPGs with slow battles these days, although I do plan to give the game a shot...sometime.
Left 4 Dead looked awesome, I love co-op games in general, especially when they're designed entirely around co-op. But I always thought this would be more like a mod-like game for PC or something, it's actually a full-fledged game? 'Cause I noticed it's coming out for 360 as well...but I don't know if I would be willing to pay 60 bucks for it unless it has a lot of content and levels. It sounded like it didn't have much of a single-player mode.
Halo 2, I didn't care about much. Never even played it in multiplayer.