Everybody knows about guys like Amir Khan, Andre Ward, Berto.
But there are some good prospects that are a bit more under the radar, a bit harder to see their fights. I'm bored so I tried to find some youtube footage for most of these guys but couldn't. Guys like the Peterson brothers, Lamont and Anthony. Jean Pascal, a 168 pounder from Canada who's probably the best RJ imitator out there. Jonathan Banks is a pretty good cruiserweight prospect. James Kirkland is a 154 pounder that fights a bit like Terry Norris. Also like Juan Manuel Lopez, the (I think) bantamweight from Puerto Rico.
One guy that's never on American TV is Jorge Linares. He fights out of Japan. He's a 130 pounder, good size, good technique overall, good jab, good body work, pretty smart fighter for a prospect. According to maxboxing.com he gave Pacman good sparring and embarrassed Ponce de Leon (Linares was fighting at 126 at the time, Ponce 122). Here's a clip, I think he could be pretty good: