I've got to toot my own horn regarding this topic. A couple years ago my
label released a Styx Tribute album called "Too Much Time On Our Hands"
featuring mostly Americana acts (with a few poppier bands, too).

The strangest tune on the record was Alt-Country songwriter Jim Roll doing a
Tom Waits-goes-crazy interpretation of "Babe."

My personal faves were Tom Freund (with Jon Brion) covering "Blue Collar
Man" with upright bass and Hammond organ, and Alva Star doing a
Prince-inspired take on "Lady."

And I got to play "Come Sail Away" on the banjo.

More info here:
http://www.saltlady.com/tribute.htm

Speaking of Tribute Albums in general, I recently got the triple-disc Peter
Case Tribute (by similarly-styled folkie artists) and I'm not too impressed
with it as a whole (although there are a few brilliant moments, like James
McMurtry' "Old Part of Town" for example).

Jonathan Rundman
http://www.jonathanrundman.com