Netrix is a free tetris clone which you can Play in either single or multiplayer. You can play it in your browser, in either Mac or Windows.
It is also available as a widget for Mac OS X 10.4 or newer.
Try topping the high scores in single-player (show highscores) or Create a game to defeat your friends! ;-)
What's new in version 1.1.3
Bug Fixes:
Improved sound effects, should remove the unwanted noises.