Scott Michael's newer books on families of fish are great! Like the Angels and butterflies book, damsel book, wrasse book, and basslet book.
Also Wittenrich's breeder's book is a great reference for pairing different fish and raising them. Many people still believe lots of fish can't be kept with their own species.
Kiysohi Endoh has a great book on angels.
Rudie Kuiter has a great series: one on angels, one on butterflies, one on fairy wrasses, one on surgeonfish, and one on seahorses. Like someone else said they don't offer much on captive care, but are great references for size and different species. With lots of interesting facts.
I also just picked up the Hawaiian Reef Fishes book by John P. Hoover and it is also a great resource.