Oh yeah, CoD4 as well.

Out of all the games purchased this generation, it would definitely have to be Unreal Tournament III on PS3.

Had it since 2007 and it is still my favorite online shooter because of the awesome weapons and super fast pacing.

Until Killzone 3 (Which I have dumped ~20 multiplayer hours into already) it was my main online game. Not 100% sure if it will stay that way though. I will have to see if Killzone 3 has that same staying power for me. So far it does.

I play tons of Nintendo classics from time to time, currently im playing A link to the past and DKcountry1.

On PC my most played game is Enemy Territory; Quake Wars, released in 07, a truly great shooter but not well known at all. I still play it frequently.

I won't make a list.  I'll just say that yesterday, I was at my mom's house while my car was being worked on.  We broke out my old Super Nes and played Tetris Attack for over an hour.  Too much fun!

All the old Lucasarts adventures
Battle Zone

If we're talking more than a year ago, FF 13, i still have to beat that game, but it's so damn boring its like a job that i hate and im not getting paid for, last chapter. GoD of War Collection, never gets old, Heavy Rain, playing with Move. Virtua Fighter 5, Tekken 6, fighters never get old. Dissidia, stupid amount of content. Braid, Penny Arcade Adventures,
Mario & Luigi BIS, i was late to the party.