what are some of the best games for Linux?

Try Battle for Wesntoh (GREAT, been playing it off and on for 4 or 3 years)
Urban Terror (pretty good FPS. The better you’ll find)
Penumbra: Oberture (First person, not shooter though. EXCELENT game. Has its first and third too. You have to pay, though)
Braid (You have to pay too, but it’s a great puzzle game with awesome music and story-line)

Strategy: 0AD, Glest, Warzone 2100
1st Person: Xonotic, Alien Arena, Americas Army

These games are native linux games. You can also play windows games under linux using the program “wine”