Pacific Fighters (+ Forgotten Battles + Aces Expansion Pack)
BEST GAME EVER. WWII flight sim with about a billion flyable planes and realistic (enough - don't visit their forums and talk about realism though... sheesh) flight model. Good range of online play options from arcade-tastic to I-wish-I-were-the-love-child-of-Biggles-and-Hermann-Goering-real. I get a little upset that shipping doesn't try and dodge torpedoes though.
MS Flight Sim 2004
Lock On: Modern Air Combat
X-Plane
Detecting a theme?
Rome: Total War
And Medieval Total War. Best RTS/turn based strategy game there is (with the exception of Harpoon). I still feel happy remembering the time I crushed Gengis Khan's entire army in a single epic battle. I was so proud of my brave little soldiers.
Half Life 2
When I want to shoot people in the face without a cockpit windshield in the way. Great pretties, good atmosphere (though the canals were a little tiresome), and reasonable plot.
SF CAVE!!!!!
BEST GAME EVER AS WELL, APART FROM ALL THE OTHER GAMES BETTER THAN IT. Best score: 3795.
http://www.sfcave.com/javaCave.php