Tetris

Free Tetris
Flash-based online game featuring ten levels and score.
http://www.freetetris.org/

Hextris
Rotate and place hexagonal pieces on the board in this online version of Tetris in Java.
http://www.hextris.com/

Java Tetris
Online Tetris game with piece preview and ten different speeds. Java source code is freely available.
http://www.percederberg.net/home/java/tetris/tetris.html

JTed
A Columns clone. Includes top 30 highscores, licensing rules for webmasters, statistics and game which includes 2 lives, sound and the option to change speed.
http://www.jted.com/

Multris
Realtime multiplayer game that you can play directly in your web-browser, no plug-ins needed. (Java)
http://www.multris.com

Netris
Play Tetris online.
http://www.emeline.com/tetris/netris.html

Swoj.com Tetris
Online version of Tetris puzzle game including high score tables.
http://www.swoj.com/tetris/

Tetris
Tetris game featuring daily highscore lists.
http://www.yook.de/tetris/

Tetris
Java implementation written Edwin Martin. Features screen buttons, as well as keyboard interface.
http://www.bitstorm.org/tetris/

Tetris Love
Tetris game reviews, history and links to 10 Tetris web games.
http://members.fortunecity.com/tetrislove/