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.
I love this post. This is a very weird cover of a song that was already weird. The video is also disturbing, which kinda did it for me. https://www.youtube.com/watch?v=KRdDTz8wL30
The original: https://www.youtube.com/watch?v=1mR6zmSTDNE