I just finished a book by Alex Kershaw called "The Few". Its about the american pilots who snuck out of the states and fought for the RAF. It was an interesting read, eight pilots (all who left while the US was nuetral) are discussed in detail. Sadly, all but one died in combat, most just after the battle of Britain.
There is also some very interesting stories and so on from German aces of the time like (Galland is among them).
I would suggest it if you like reading about the war and the pilots who bravely fought in it.