Online simulator of Dance Dance Revolution made in Macromedia Flash. Uses the arrow keys to replace the dance pad. Not the ultimate DDR simulator, but the basic idea gets across, and it is fun. The music for FFR is divided into the categories of Dance, Hip Hop, Funk, Rock, Arcade, and Classical. Higher levels require a good amount of caffeine to complete, and even then they are difficult. This game is a good way to improve your eye-hand coordination.
Flash Flash Revolution can be played for free at http://www.flashflashrevolution.com.