I see some glaring omissions for songwriter's...
For U.K and oversees, there's David Bowie and Ian Hunter (who'd probably be at the top of any most underrated list).
For American songwriter, you have to have Tom Petty in there (as well as a candidate for Rock band). Here's one of his many hits. This is also what I consider one of the best special guest performances. Typically when an established act brings on a special guest for one their numbers, it's either underwhelming, forgettable, or a bit of a train wreck. I think this one is top shelf.
(Is that Benmont Tensch or Elliot Spitzer?)
For U.K and oversees, there's David Bowie and Ian Hunter (who'd probably be at the top of any most underrated list).
For American songwriter, you have to have Tom Petty in there (as well as a candidate for Rock band). Here's one of his many hits. This is also what I consider one of the best special guest performances. Typically when an established act brings on a special guest for one their numbers, it's either underwhelming, forgettable, or a bit of a train wreck. I think this one is top shelf.
(Is that Benmont Tensch or Elliot Spitzer?)