The first Annual ROBOLympics took place in San Francisco, California, US.

They were held on March 20th and 21st 2004.

The ROBOlympics official site

Events include Soccer, Sumo, Fire-Fighting, Maze-Solving and a great deal more...

It is an excellent way to encourage innovation, and allow some of the most crazy robot builders on the planet to meet each other and swap ideas.