Play Cool Math has released this lovely looking mahjong solitaire game. Brand new levels are added every day (currently there are over 170 of them) and the game features 3 skins, Facebook connect, high scores, browser back-ups (restored if you close your browser by accident), an undo feature, magic help and more!
If you enjoy mahjong solitaire then this is well worth checking out. Some of the levels are simply brilliant.