If you like strategy games then I would try Company of Heroes. It is a WWII real time strategy game that is loosely based on historical events. Very cool.
Also, even though I don't have it yet, I would recommend the Orange Box. If you haven't played Half Life 2, then it comes with the original game plus Episodes I, II, Portal and Team Fortress 2 (multiplayer shooter). I'm playing HL2 for the second time around so that I can play Epi I, II when I get the Orange Box. Also heard great things about Team Fortress 2.
"Think of how stupid the average person is, and realize half of them are stupider than that." ~George Carlin