I play Travian (S5 and S1, just got wiped out on S4 and gave up). I'm getting burned out on Travian, though. There is nothing to deter huge players from crushing small players, diplomacy is a waste of time, and unlike ogame, you can lose everything in a matter of minutes. Back to square one is a bad place to be on a game that has a definite end-game point. Ogame is far better (IMO), as you might lose you ability to attack, but your ability to gather resources and rebuild is not compromised. I especially hate the fact that you can build a colony on Travian all the way up, only to have another player take it for theirs. It means the big get bigger and the small get gone. While that might be realistic in a narrow view, it make strategy all but meaningless. Get biggest fastest, you win. If you can do that by stepping on everyone around you, so much the better. Ogame is better.
I "play" (if you can call it that) Kingdom of Loathing for laughs. My office mates and I have a clan and it is a fun time waster on a slow afternoon, or while waiting for the caffeine to kick in first thing in the morning. :p
I also play TF2 when I have a block of time to waste. I love FPS games, but I'm pretty busy. I can play ogame from work (yay for computer intensive job - "I'm stress testing the network boss") and class (yay WiFi and inattentive teachers). If I have time free on a weekend, a bit of scotch and a few hours of head shots is just good for the soul.
My oldest addiction is table top RPG games, and those have nicely migrated to email/forums. I run and play a number of RPGs (mostly the Shadowrun genre) on the forum rpol.net, and via email lists.