Dave Grohl covered many bands, and played many alternate versions of his songs.
There are also a lot of side projects like Probot.

Live Covers

Baby Hold On To Me (Eddie Money)
Blackbird (Beatles)
Born In The Bayou (Creedence Clearwater Revival)
Bullet With Butterfly Wings (Smashing Pumpkins)
Cactus (Pixies)
Carry On My Wayward Son (Kansas)
Keep The Car Running (Arcade Fire)
Lovin' Touchin' Squeezin' (Journey)
Never Talking To You Again (Husker Du)
Now I'm Here (Queen)
Stairway To Heaven (Led Zeppelin)
Tie Your Mother Down (Queen)
Tiny Dancer (Elton John)
With Arms Wide Open (Creed)