The question has been closed for the following reason "The question is answered, right answer was accepted" by grooveDexter Mar 15 '13 at 15:49
This one right here is the best on the web:
Just type in the letters you have, and the letter on the board you will build off of. It will tell you every single possible combination for Words with Friends.
Please note that Words with Friends does not use the same dictionary as Scrabble, so obscure words that work in one may not work in the other. But this site thought ahead and there are individual webapps for both games.
answered Mar 15 '13 at 15:49