The voice recording group for TomTom GPS is known for bringing in famous voices to be offered as optional downloads for its GPS devices. They started doing videos of the recording sessions, and they're pretty good.
I must say, it's much more interesting than the voice of Ozzy. A family member of mine heard that one, and he basically yells and swears at you for every instruction. You can't really understand what he says, so it's not very useful for navigation. Unless you're on Ozzy fan.