This little flash ping pong game that started earlier this year seems to have gained popularity with more and more sites hosting their version with different players to play against.
The original one I found back in February was one game to 21, switch after 5 serves. I've seen various other styles since but today I stumbled on one hosted at ITTF (International Table Tennis Federation) that plays by Olympic rules. Games go to 11, switch after 2 serves and best of 3 games. Different players, different physics, worth a try if you enjoyed the last game.