I found this interesting site: Экзотические шашки (Exotic checkers). It is in russian language, but there are enough diagramms. Beside other checkers variants, it contains three chess+checkers variants.
(hide) If you want to find an opponent with similar playing skills to your own look in the Ratings page of the type of game you want and find a player with a similar BKR. (pauloaguia) (show all tips)