While the list could go on and on, these are some of the more common names if you're familiar with SEC football that probably job your memory. Terry Beckner Jr., Bryce Brown and Calvin Ashley would be some others to name a few.
It's worth nothing that when players are seen as busts, the lack of production isn't always their fault. In the case of Russell Shepard, he was misused. With Shea Patterson, an unforeseen coaching change effected things.
The debate will always go on over whether or not players were busts in general, who the biggest ones were, etc. Regardless of your side, its intriguing to think about "what could have been."