Here are a few to get things started:
Don Henley’s The Boys of Summer as an 80s synth tune
Bossa nova version of Crowded House’s Don’t Dream It’s Over
Reggae-ish version of Aretha Franklin’s Respect
A capella men’s ensemble version of Lady Gaga’s Bad Romance
EDIT: This has been great, everyone. Thanks to everyone for all the terrific links and for introducing me to a number of artists I wouldn’t have heard of otherwise. Seriously, the online rabbit-holes have been thoroughly enjoyable–even it I stayed up a bit too late a number of times.
Worth it.
Bantamweight’s haunting cover of Nirvana’s Heart Shaped Box is sorely underrated in my opinion.
ERRA’s versions of Audioslave’s Light My Way and Muse’s Stockholm Syndrome.
Art vs Science’s psychedelic-funk cover of Enter Sandman featuring a sweet as keytar solo.
Sleep Token’s heartwrenching unplugged version of Hey Ya!.
And finally, Denzel Curry’s supercharged version of Bulls on Parade. I didn’t think the track could sound angrier but he’s gone and done it.
Bonus: Andrew Hulshult’s Hell March, featuring chainguns as percussion, Master Boot Record’s Doom E1M1 metal chiptune remix, and GeoffPlaysGuitar’s argent-metalized Halo Overture.