Just out of curiosity :)
I'm playing Giants: Citizen Kabuto and Fallout 3
What are you playing? post it here

Need For Speed Underground (Undercover sucked so I have to)
World Championship Snooker 2005 (classic)
Crayon Physics Deluxe (nice indie game)
Defense Grid - The Awakening (great TD game)
Serious Sam 2 (want to finish it on Serious difficulty again)
Worms Armageddon (as always)
All of these on my lovely PC. Not a console player really, though I own a PS2 and a GBA.

Fallout 2, Jagged Alliance 2, Storm of Zehir, Simon the Sorceror and Red Alert 3. (although not necessarily in that order, nor at the same time!)

At the moment mostly Giants: Citizen Kabuto and GTA Vice City.

Sports Car GT
Fallout 3
Cave Story
Arx Fatalis
The Witcher
..in no particular order (although I am thrashing Sports Car somewhat recently...!!?)

I'm finishing up Avernum V for the second time (my first party blew pretty hard, Avernum IV party compositions don't seem to work so well in V).
Meanwhile I've started up a game of Temple of Elemental Evil, I play a little Disciples II on the side.

Neverwinter Nights Original Campaign
Team Fortress 2 (since day 1)
Left 4 Dead (since day 1)
Half-Life
Diablo II

It's true you can do that in most levels, but there's various gamemodes and such, so I think it is pretty good.

(That's the list for today... I never play any single game very long, so I currently rotate between 20 or so games)
Quake - Because I just love this game... and it's amazing what you get with realtime lighting, 2GB of new textures, HDR overbrights and so on and so forth
Broken Sword 2 - had to try the new video files (sadly, I seem to have misplaced my CDs and the version I have on PC is one that I actually reencoded for my Palm, which means very low audio quality)
Broken Sword 3 - No reason, I just like it.
Burnout Paradise - Wanted to race a friend (PS3)
CoD 5 - mainly fun for the Nazi Zombie mode (PS3)
Prince of Persia - Because sometimes I like old fashioned button smashing. That and the dialog is amazingly well written (PS3)
Test Drive Unlimited - Maybe not the best racing game, but there's lots to explore (PSP)

Just beat Resident Evil Wii on Quake 4 on PC. Planning to finish the extra missions that you unlock when beating Resident Evil and replay Quake 4 on a higher difficulty so you might say that I'm still playing them.

Well, Angband just reached the beta stage of v3.1...
Aside from that, just Freespace 1. Most games have been removed from this PC as the new one should arrive in a couple of days, and I don't want to get part way through something then forget about it during the shift.

The Lord of the Rings Online, PC - I spend way too much time playing this :P
The Witcher, PC - Playing through for the first time - just hit Act 2
Super Street Fighter II Turbo HD Remix, Xbox360 - hadoken!
Crysis Warhead, PC - trying to get back into this, was fun initially but I lost interest for some reason
Pro Evolution Soccer 2009, Xbox 360 - frustrates the hell out of me, but still fun for a kick-around occasionally
That's it at the moment, Want to get back and finish Mass Effect eventually, it would be much easier if I didn't have to work full-time :(

Currently alternating between Disciples 2 (good TBS games are like crack for me) and Arx Fatalis.

Currently on my third run through Storm of Zehir. Can't seem to tear myself away from it.