Take a look at Raul Cruz, mexican Bantamweight. Of his first 22 fights 10 of them involved an opponent who was, went on to become or had been a world champ. Another one went on to lose a split decision for the bantamweight title. His last fight was against Danny Lopez. http://www.boxrec.com/list_bouts.php?human_id=12002&cat=boxer
Vargas is my choice but it didnt do weel to him! if he have fought like a lot of other boxer and choose carefully he could still be fighting but he took the short way and look really impressive but he was washed at 26years old!
Oscar De La Hoya and Kostya Tszyu are the first two that come to mind. EDIT: Why is my post count so low? What have I missed? Another crash?