I just got lemmings revolutions-it's pure mouse driven crack. Like flippy said, rts games can usualy be mouse driven, as can most of the Sim series of games, and in that same vein Pharoh is pretty easy to navigate with just a mouse. Most 4x games can be easily mouse controled also, like Alpha Centauri. I'd highly recomend "The Longest Journey" it's an adventure game of the old style (KQ, QfG, SQ, etc) and absolutely wonderful and cheap. If puzzles are your thing, might check out
www.popcap.com -all of their games you can play online, or purchase to play off. Myst is a classic point and click adventure, although I haven't played the sequels, and I'm not sure how it stand up to the test of time. The game CSI isn't actualy all that bad, although woefully short. If you're on a mac by any chance, google Barrack and download it now.