A lot of usual names have already been mentioned so I will throw a couple of others out there.
For biggest bust, I put forward Charles Rogers. He may have been the best college receiver I have ever seen. He had it all: size, speed, hands, routes, finesse. The whole Michigan State offense was essentially have Jeff Smoker heave up something to Rogers and pray he found a way to come down with. Every single time he did. For those Bengals fans, they probably remember former Michigan standout CB Marlin Jackson. He had a great NFL career. Rogers would make him look like a middle schooler every single season. He was the 2nd overall pick by the Lions, but Rogers broke his clavicle in back-to-back seasons at the start of his career. Got addicted to pain killers and was basically done.
For biggest surprise, I will go with Terrell Davis. Started at a junior college. Transferred to Georgia and only really the main starter his senior year. Put up good buy not incredible numbers for a terrible Bulldogs team and was a 6th round pick. Turned that into a Hall of Fame career. Georgia had put out a string of incredible college backs who had amazing college careers, but never became NFL superstars like Tim Worley, Rodney Hampton and Garrison Hearst. Davis was an afterthought in college compared to those players, yet somehow, he was better than all three.