http://www.vivi.com
This is one of my favorite online games. It is a boxing game that is free to play. They just want you to click thier banners every now and then.
The game is based on math based formulas for fight plans. There is a rank board and each night has a different weight class fighting. I quit playing because it was so addictive. Took way too much of my time.
Check it out.
Linear Mode
