Out of the ones mentioned above I'd reccomend "Vendetta" by Paul Ferris and Reg Mckay, or "Essex boys" (fuck all like the film and MUCH better) by Bernard O'mahony(sp?). Looking for a good one to read very soon, i usually make a point of reading one when I'm sunning it by the pool in my annual pilgramage to spain.
I've also got a "Cosa Nostra" book, but i haven't read it all yet, so might make a start on that now that I've read this thread actually.