Just read Gravano's Underboss for the first time, it was alright, but didn't find out anything I already knew..

Just began with 'The Last Godfathers' by John Follain. It's about the rise and fall of the Corleonesi. I'm at page 80 at the moment but I can't put it away, it's one of the best true crime books I've ever read. His prose is superb. When he, for example, describes the assassination of Falcone, something I already know how and when it took place, he still manages to create suspense and get you right in the middle of it.
I can really recommend this book to everybody who wants to know more about the Sicilian Mafia..