I like Munchkin and Magic: The Gathering .. Card games have almost exclusively been part of the nerdy side to my existence.
Munchkin is the most entertaining of the two. Me and the GF played it a lot with other friends the last time we were up in the arctic where there's not always such a lot to do in the dark season. The rules in the game are not very straightforward which leads to loud arguments with people getting up from their chairs, shouting across the table .. it's awesome!