Checkers

Browser War Checkers
A JavaScript based game themed on the second browser war. Offers two difficulty levels and an undo option.
http://www.7is7.com/software/games/checkers/checkers.html

Checkers Alice In Wonderland
A flash based game. Play all thoe creatures from wonderland. Moves up levels as you win.
http://www.gameshot.org/?id=2082

Chinook
Play against the world champion program online, reduced in chance to give players a chance of drawing. Publications, endgame database, game records. Watch ongoing games.
http://games.cs.ualberta.ca/~chinook/play/

Darkfish
A Java applet implementation. Pieces touched must be played.
http://www.darkfish.com/checkers/

JavaFile.com
A freely available JavaScript based version, though the board setup is wrong and errors occur.
http://www.javafile.com/games/checkers/checkers.php