How about the Electric Mayhem singing "Y.M.C.A." by The Village People  (or has that been done?  please tell me if it has, I really like that song!  )
(the tune, ok.  I didn't know what the song was even about until many years after I'd heard it as a child- it's still good for roller skating parties!)
  
  
  
  
The Muppets already have done my all time favorite Beach Boys song, which of course, is "Kokomo".
I could see them doing some other 80s songs though.
Like "She Drives Me Crazy" by Fine Young Cannibals-  wait... They DID do that on the "Kermit Unpigged" album
hmm...  Okay, how about "The Power of Love" by Huey Lewis and the News.
I think I could see the Electric Mayhem doing that.  (Although I guess Kermit and Miss Piggy could too...)
Well, here's one that would work well for graphic imagery.
"To **** With the Devil" by Stryper.  I could just see one of the devil muppets from "The Devil Went Down to Georgia" skit getting stuffed into an abyss.
"Pressing On" by Relient K.  That's just a really encouraging song for me that could be done well by Kermit, what with the hectic schedule of running a theatre and all.
"Beyond Belief" by Petra.  It's a song about taking your faith in Christ to a deeper level and following where God leads.  And it totally rocks!  This is definitely one for the Electric Mayhem.
And I definitely vote for "The Pirates Who Don't Do Anything", a song from the Veggietales gang, of course, and later covered by Relient K.
I'm sure there's lots of other good ones, and there's so many songs that I like I might find myself posting more later....