Lots of great ones mentioned already.
I suppose this one tops my list. Boz Scaggs, w/Duane Allman featured, Loan Me a Dime, originally by Fenton Robinson.
regarding Dylan, I like Jimi's Like a Rolling Stone. And Johnny Rivers' Positively 4th Street, below.
Linda had dozens, I don't know where to start. I liked the Motown covers (The Tracks of my Tears, Heat Wave, You're No Good, Rescue Me). I liked the Elvis Costello covers (Girls' Talk, Party Girl, Talking in the Dark). I'll submit Willin', originated by Lowell George, below.
Elvis C. covered a few songs. This Nick Lowe/Brinsley Schwartz (the band, not the man) tune, (What's So Funny 'Bout) Peace, Love, and Understanding, below.
Graham Parker has several good covers. Ann Peebles' I'm Gonna Tear Your Playhouse Down, with his band The Rumour. And by himself, Comfortably Numb from the Pink Floyd.
Finally, Michael Franti and the Disposable Heroes of Hiphoprisy covering Jello/Dead Kennedys' California Uber Alles
But geez, we could go all weekend, so many great covers. Hope that isn't too many.