There are some pretty good free online games around that you might not know about. I'll try to give one props every Wednesday, my lasiest day.
First up: Cyrkam Airtos. A simple flash game, "Airtos" lets you sit in an office and chuck balls of paper into a bin. All the details, from the excellent physics to the bleepy soundtrack, add up to make this possibly the most entertaining timewaster around. This is a piece of fun.