Like word puzzles? Then try your hand at Imangi, the fun new iPhone game that challenges your vocabulary and spatial reasoning skills.
http://www.imangistudios.com/imangi.html

A word square is a grid of letters where each row and column forms a valid word. In Imangi Word Squares, you start with a scrambled word square, and it's your job to unscramble the letters.
http://www.imangistudios.com/wordsquares/index.html

For me this is the most fun scrabble interface.
http://www.scrabble.com