Dragonology by Ernest Drake (I think) is very good, but it is more like an encyklopedia, in the sense that it describes different types and so on. However it is very entertaining and has beautiful illustrations.
Temeraire series is also very good, it is set in the time of Napolean wars and dragons exist, so Britain has Royal Air Force of dragons. It is very nicely written, funny at some parts, the universe is well thought out. The series has six books in total I think.