My games of the year (based upon how much time I have played them):
Oblivion - This is the game I have sunk the most time into. The first game that I have created mods for as well.
World of Wacraft - A close second. Played this since release and still do occasionally. Waiting on the expansion now. If you count last year as well, this game would account for more game play time than all other games I have played combined.
Silent Hunter III - A good find this one was.
Battlefield 2142 - Really got into this one for awhile. Me and my roomate both play so it's great to team up and kick some ass. Haven't played for a bit though. SH3 can be blamed for that.
Medieval 2 - A good strategy game, but over the years my interest in this genre has waned. C&C3 though does look good.
Falcon 4.0 - My new obsession.
Infinity: The Quest for Earth (Combat Prototype) - A space sim MMO that is currently being developed. A combat prototype is out as a free download which includes limited multiplayer. Been looking forward to this one and have contributed some to it (a ship model).