Mahjong Titans

Mahjong Solitaire
 - Play Mahjong Titans Online

Because the game is so popular, many people are reffering to this as Mah Jong or Mah-jongg.
On the Mahjong titans website you can play 5 variants of the game.
The most played versions are Mahjong connect and Mahjong Solitaire.
If you want to try something new, take a look at Mahjong Tiles, which have animated tiles.
Mahjong Dimensions 3D has a modern look, sometimes a nice change, even if MahJong is an ancient game.