The World's Fastest Scrabble Program (1988) [pdf] (cs.cmu.edu)

Better pdf at http://www.gtoal.com/wordgames/jacobson+appel/aj.pdf

Source code at http://www.gtoal.com/wordgames/jacobson+appel/mac/Crab_sourc...

IIRC this was beaten later by Steven Gordon's GADDAG algorithm.

Edit: yep. Fixed name. Here's the Wikipedia link:

http://en.m.wikipedia.org/wiki/GADDAG

I've written a very fast Scrabble program in JavaScript which I think should perform on par with it (i.e greedy algorithm that chooses word with best possible score for the next move)

http://amnond.github.io/jscrab/