Aside from all the other online dictionaries, Scrabble players may be interested in the following sites:
Hasbro’s word lists for tough times (including Q without U, two letter words, X words, and more). Wordplays.com’s tools for word games is a collection of web apps that would be handy to use (if it were legal to do so) during a game. Mark has developed a number of word lists and other scrabble tools. And we can’t ignore the word lists from the Internet Scrabble Club or the ENABLE dictionary.