Scott Michael's "Pocket Expert Guide to Marine Fishes" is also worth every cent. I bring it with me whenever I buy new fish. Saved my corals from becoming someone's lunch more than once.
I don't know about Vol2 but I got Vol1. It is one of the best referances I never go fish shopping or looking for a possible purchase without it. Just be carefull it can cause arguments with the "Tang Police" as for some reason alot of people seem to think you need larger tanks for tangs then is listed. Oh and when it list Max Size that is Max size ever recorded on record anywhere, the biggest wheather in tank ocean, or whatever.
Aquarium Corals from Borneman is also very good. Good info on care and gotta love the photos. I also have Vol 1 of Scott's series and love it. It goes into great detail on care for each fish it covors.
One book I have wanted for awhile but couldnt stomach the price untill now was JEN Vernon's Corals of the world. It is amazing expecially for us SPS lovers. The photos are great showing many variations of coral growth within one spieces dependant on enviromental conditions and skeletal photos as well. Its the best book set I have ever bought.
I second Ben and Minime. If you don't want to dig for the posts that praise Borneman's Aquarium Corals I'll be happy to save you the time. Excellent text. I would consider it a "must have" for any reefkeeper's library.