Hasbro Scrabble

Includes an anagram builder, a dictionary, and links to various Scrabble related sites.
http://www.hasbroscrabble.com/home.html

Eric Harshbarger's Scrabble Challenges

Provides Scrabble challenges for advanced players.
http://www.ericharshbarger.org/scrabble/

The Scrabble Rack

Offers wordlists for two and three letter words, a word finder and a word checker.
http://www.boulter.com/scrabble/

Mattel Scrabble

Three Shockwave games: Scrabble Hangman, Scrabble Invaders and Scrabble Snake.
http://www.mattelscrabble.com/en/kids/

BigDoggy's Scrabble Strategy Hints

Provides articles on becoming a better player.
http://www.cyberonic.com/~bigdoggy/strategy.html