I've installed a handful of games, only to remove them after a few days. A few I have found recently have actually impressed me enough to keep around.
Modern Conflict - I mentioned this a while back, but it was demo only then. The full version is finally out. Think Risk on steroids.
Osmos - Not the cheapest game, but its very pleasing to play. Great music and amazing visual appeal.
Dizzy Pad - simple, addictive. Also very visually appealing.
Harbor Master - Yeah, everyone has heard of this one. I just got around to installing it. It really is good.