Like Kelly said, FIRST had Mandy Moore in 2002. Here are two old threads discussing that:
http://www.chiefdelphi.com/forums/showthread.php?t=4039 and
http://www.chiefdelphi.com/forums/showthread.php?t=3949
With that being said, If FIRST were able to get the Blue Man Group (without breaking the bank) they should absolutely go for it. There are few (if any) major bands that would be more appropriate.