coan.net: As for an easy variant to add, if Draughts ("International Checkers") is created, is Canadian checkers. It has the same rules as Draughts, except that's it's played on a 12x12 board (with 30 checkers).
Wikipedia has a handy table which lists the differences between the regional draughts/checkers variants, and has links to some "invented" variants.
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)