In 1997, Stone Temple Pilots frontman Scott Weiland released 12 Bar Blues, his first solo album, with the single “Lady Your Roof Brings Me Down”. This song featured an unusual but notable accompaniment: accordion played by Sheryl Crow.
What are some other commercially released songs with unusual but notable musical contributions?
Tobias_flenderz t1_j1x028h wrote
Two members of Red Hot Chili Peppers (Navarro, Flea) played instruments on Alanis Morissette's You Oughtta Know.They were playing the instruments they were known for, however.Flea also appeared on The Mars Volta song The Widow, this time playing the trumpet. That one definitely fits your post.
I will post more as I think of them.