Below are some links for sudoku sites... Please add if you have others that you play!
Completely Free and great for regular sudoku, no super games!
Krazy Dad's You have to sign up for an account, but get one free puzzle a day...
Super Soduko Puzzles for both regular and super, and a good solver if you get desperate!
Mark Byers Sudoku Regular sudoku, both online and printable...
Web Sudoku