Surprised nobody has said Hasheem Thabeet yet. I know a lot of people thought he was kind of awkward/scrawny to standout in the NBA, but guys who are 7'3 and athletic like that don't come along very often.
TJ Ford is another guy that comes to mind. True story, I went to one of LeBron's first summer league games in Boston and T.J. Ford put on a show. The crowd was chanting "TJ's better!" throughout the game.
I thought Chris Douglas-Roberts was going to have a nice, long career in the NBA also. He was never too athetic but he had a crafty game that I thought would translate better to the NBA.