RebelForce Radio (a Star Wars radio show and podcast) recently recorded a live commentary of Star Wars with actor Sam Witwer. If you've got the film on Blu-Ray (I don't), you can cue it up to play in sync with the commentary as you listen.
Witwer has been a voice actor in the Clone Wars TV show and in a number of LucasArts video games. I don't know much about him and frankly didn't expect much. I was pleasantly surprised by how thoughtful and informed his commentary was.