A couple others:

As noted above, the ASA books are pretty critical if your interview involves some kind of ATP-like test. The books have all the answers and explainations as to why certain answers are right or wrong.

Also, just ordered the Encyclopedia of Technical Aviation. Not cheap, but you can get it on Amazon. Good for reviewing topics you come across in your studies since everything is alphabetical and therefore easy to look up and research further.

Lastly, I printed "Weather for Aircrews" from the USAF (AFI 11-203, March 1997). It's a great "Weather 101" type of pub, and it's free (except for the paper and printer ink). Google "weather for aircrews" and pull it off the USAF pubs site.