I Love Acoustic Versions.
I agree with whoever said Travis' version of 'Baby, One More Time". It actually makes you realize what a good pop song that is. Richard Thompson also does an acoustic version of that which is also good. Two of my favorites that aren't very well known are Kathryn William's acoustic version of Nirvana's "All Apologies" (eerie and chilling) and Josh Rouse's acoustic version of The Clash's "Straight to Hell" (just really really good).