http://www.uvmegameworld.com/
This site launches on TODAY. I was a beta tester and its awesome. You can place small wagers on sudoku games and challenge friends and others.
On top of all that the site has a social network and instant message. The site will not be up until monday as they shut it down after all the beta testing to make all the changes before the launch.
I have not been this fired up since I started playing Sudoku online. I am addicted to it haha.