In my second semester, freshman year of college, I probably spent three hours playing cards for every hour I spent in class (or at least, for every hour I was supposed to be in class). At the time, we mainly played Bridge, Hearts, and a bit of Spades.

In the last year, on a couple of occasions I've had a chance to relive the card playing with a couple of my college buddies. The game of choice has been Barbu - a 4 player game that takes about 2 hours to play (you play a structured set of 28 hands). It's got elements of Bridge, Hearts, and Spades, plus a few twists. Very fun. Here's a Barbu rules page, and here's the custom Barbu scoresheet my friend (Steve Rareshide) created, which also contains an abbreviated version of the rules. (Note that the different sources have the Barbu scoring slightly different. It's a lot of fun - if you're a card player, check it out some night.