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

Probot (feat. Dave Grohl)

01. Centuries Of Sin (w/ Cronos / Venom)
02. Red War (w/ Max Cavalera / Soulfly, Sepultura)
03. Shake Your Blood (w/ Lemmy / Motörhead)
04. Access Babylon (w/ Mike Dean / C.O.C.)
05. Silent Spring (w/ Kurt Brecht / D.R.I.)
06. Ice Cold Man (w/ Lee Dorrian / Cathedral / Napalm Death)
07. The Emerald Law (w/ Wino / Place Of Skulls / The Obsessed)
08. Big Sky (w/ Tom G. Warrior / Celtic Frost)
09. Dictatorsaurus (w/ Snake / Voïvod)
10. My Tortured Soul (w/ Eric Wagner / Trouble)
11. Sweet Dreams (w/ King Diamond / Mercyful Fate)
12. I Am The Warlock (w/ Jack Black / Tenacious D)