FunTown Mahjong combines the fun and addictiveness of the ancient Chinese tile game with all the modern bells and whistles, including Xbox Live online play, leaderboards, and tons of game variations. You can purchase the full game for 800 points, and then slap down an additional 160 points for the Chinese Festival pack, which allows you to play in a temple during the Chinese New Year. You know, for luck.
Of course the best part of any video game version of Mahjong? Not having to set up the damn tiles yourself.
Arcade: FunTown Mahjong (and DLC) [Xbox Live's Major Nelson]