I've created wordlists from Wikipedia database dumps some time ago (http://benjamin-schweizer.de/files/wordlist-wikipedia/); they are pretty large and thus, useful for dictionary attacks. The wordlists are sorted, common words are on top of the lists.

I think that there is a typical password length, so you could improve the sorting based upon a multi-dimensional rating scheme. I'd use expected password length and commonness of a word as factors. Mixing these real words with computer generated words might speed up brute force attacks.

However, I'm not sure how to integrate ordered wordfiles with rainbow tables. Any ideas?