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. Thank you all for 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 if I stayed up a bit too late a number of times.
Worth it.
The Persuasions - Anyway the Wind Blows by Frank Zappa
Kind of a pretty straight cover, but I think by stripping it down to just melody and vocals shows just how good and faithful to the genre the original was.
The whole Persuasions album of Zappa songs is terrific. Definitely recommend.
Nirvana - Love Buzz
Original for reference.
It’s kind of amazing that they’re the same song, but when you listen to the original, you can hear what Kurt was picking up on. Two totally different songs but … not.