Being a huge Teenage Mutant Ninja Turtle fan, I'm very happy to see 2 actors from the new TMNT movie. Patrick Stewart and Billy West.
I would love to see Grey Delisle and Kevin Smith.
Other interesting guests:
Cam Clarke
Veronica Taylor
Townsend Coleman
James Avery
Kevin Clash
and of course LOST and BUFFY/ANGEL/FIREFLY cast are more then welcome!!!