A couple of good ones, now that I've had time to think about it:
Cobra Verde's rendition of the Pink classic "I'm comin' out".
The Saints always did great cover songs...They did a great "River Deep, Mountain High" (Ike and Tina), also did a great cover of The Missing Links' "Wild About You".
I love Australian bands. Have I ever told any of you?
The Devil Dogs were really good at cover songs, most notably "Kissing Cousins".
The Real Kids version of Buddy Holly's "Rave On" is the bee's knees.
As for bad covers, I can't think of many right now, but I will say that it's time for everyone to please stop covering "Teenage Kicks". I know it's got an infectious hook, but move on. Cover 96 Tears or something instead.
I know some of you don't like covers, but they're really a tradition as old as Rock N' Roll. I really don't have a problem with them unless the band just plays them note for note, doing nothing to add new wrinkles to make 'em their own.
Heck, when you buy an old hotrod, you still have to supe 'em up a bit.