Twilight Imperium is really great. A couple of others that I really liked is Android and Arkham Horror (different style though).

Has anyone played Diplomacy and/or Long live the King? I love their concept, although I haven't played any of them..

Slightly off-topic: I play a lot of rpg's, but for some reason I don't like their newer versions, ie d&d v3+, vampire: the requiem etc. Are there any others who have gone through the different versions? How do you feel about the most recent ones?