I had a professor at ECU who was a nationally ranked Scrabble player. He knew every Scrabble-legal 2 and 3 letter word. He showed me the word lists he studied; there were a lot of them. Things that didn't look like words.
I am a bit of a Words With Friends addict. This is a Scrabble knock-off for the iPhone and iPad. There are quite a few annoying aspects of this implementation of Scrabble, but it's the best thing out there so far in terms of capability and price.
When looking at their support site, I noticed that the word set they use is the ENABLE2K word set. This is used by a lot of games since it is in the public domain. I found a copy of it and decided to make the Enabler iPhone app that lets me create word lists to study. It's working great. I know every word that starts with a Q but isn't followed by a U. I know all the words that end in J, all the two letter words that start with J or U. Every 2, 3 and 4 letter word that starts with X. That sort of thing.
It is a free download in the app store.
I have ideas for more features, and even a quiz function to help you study. If you have any other ideas, leave them in comments here, or even better fill out the survey you can get to from the information screen on the app (that's the little 'i' icon at bottom right). And while you're on it, click on an ad :)