Best Covers

In the "hilarious" category:

"Jump" - Aztec Camera

"I Will Survive" - Cake

"Pump It Up" - Prozak For Lovers

In the "Wow, that took courage and talent to tackle that one:"

"Walk On the Wild Side" - Edie Brickell & New Bohemians

"River" - Rosanne Cash (Joni Mitchell)

"Just a Little Lovin" - Shelby Lynne [an entire album of songs done by Dusty Springfield] 

Shawn Colvin "This must be the place (naive song)". Her album "Cover Girl" is all covers and has some real gems.

Purple Rain - Inter Arma

Easy - Faith No More

Take On Me - Reel Big Fish

Holy Diver - Killswitch Engage

Africa - Weezer

tony1954:

Don't know if Joe saw this (think it came out maybe a year before his death), but he did enjoy Belushi's impression.

DeKay

So many, but #1 for me is from back in the day;

Tom Rush's cover of Joni's "Urge for Going"