Low and Slow, I'd like to endorse the opinions given by Scope Dope and Spruce Moose in recommending Derek Robinson. Not only is Piece of Cake a marvellous read, but he wrote a follow up about the Desert Air Force with some of the surviving characters from Piece of Cake. It's title is A Good Clean Fight. He's also written a couple of WW1 novels, although Goshawk Squadron is the only one I can remember. If you go to Amazon or even better
http://www.thebookplace.com, and type in Derek Robinson in the search line you'll get all his currently available books.
Laddie Lucas has edited a couple of excellent books too, particularly Out Of The Blue, a collection of stories illustrating the role of luck in air warfare. Some of the stories are hilarious, some tragic and some simply amazing, but it's well worth a read. It's currently out of print, but The Book Place found me a copy without too much trouble. I would recommend it simply on the strength of the 5 or 6 stories in the series "The Cult of the Reciprocal" - all to do with pilots heading off in the wrong direction, resulting in, amongst other things, a Beaufighter dropping mines in Liverpool harbour instead of Brest. Damn funny.
Hope this helps, and in case anyone reading this can help, I'm trying to find a copy of a book called "Let A Soldier Die", a memoir (or possibly novel, I'm not sure) about helicopters in Vietnam, and allegedly better than Chickenhawk. Seems to be out of print, but if anyone can help, I'd be very grateful