Case Files: OB/Gyn by Eugene Toy. This is a relatively new series put out by Lange (I think they have Medicine and Surgery too, but I can't comment on them). This book is awesome...i used only it and Blueprints (this is the only Blueprints I would recommend) and destroyed the shelf test.
The format is great....It's got ~40 short case presentations then goes through DDx, Tx options, pathophys, terms/definitions. Also has some quick questions. All in all, a great book to carry around on the wards/on call....anytime you have time to read 4-5 pages.