Bobby McFerrin does Ave Maria - bizarre, but I think it just about works!
It sent me looking for his and Robin Williams' version of Come Together which (from the sublime to the ridiculous) I remember as being one of the worst things I have ever heard. Alas, YouTube could not deliver this time. However, from the same George Martin tribute album is Jim Carrey's interpretation of I am the Walrus. Hmmm.
Christ, youtube has also come up with Sean Connery's version of In My Life, which strangely sounds as you would expect ("There are playshes I remember" etc) - he raps it rather than sings, which is something I suppose. Sounds kind of like Arab Strap. Don't understand what the video is about - it seems to be a tribute to Benfica FC.
I guess I've never heard George Martin talk about anything other than the Beatles, but this Big Train sketch just brought it home...
In a similar vein is the Onion's typically genius Robbie Krieger Goes 51 Minutes Without Mentioning Jim Morrison.