Just for fun! Heres some links to free games - downloads and play online

Test how good your reaction speeds are. (Warning! highly addictive)
http://www.darktick.com/

Download free classic retro games like Space Invaders and Pacman:
http://www.classic-retro-games.com/index.php

Play the Office Space game - Surviving 'til Vacation
http://www.disarea.com/work/office_space/