onemorelevel.com. I like games with interesting/unique mechanics, especially ones I can play in under 30 minutes.
I also went for the deepest dungeon award. This one didn't start very well (exactly speed 200 at the end of level 2), but by level 24, I had 60 nitros stockpiled! Good thing too, I was using almost 10 per level just to finish in 6th!