This thread is a painful reminder of the incredible "unplugged" vault material that MTV is sitting on. Consider some of the bands that have appeared that haven't had an officially-released recording:
The Alarm
The Allman Brothers
The Black Crowes/Tesla
Crosby, Stills and Nash
Crowded House
The Corrs
The Cure
Duran Duran
Elvis Costello
Live (not a huge fan, but this was an incredible performance)
REM (twice)
Seal
Michelle Shocked/Indigo Girls
Squeeze
10,000 Maniacs (they appeared twice; would love to have the original performance on CD)
The Smithereens/Graham Parker
Stevie Ray Vaughan/Joe Satriani
The Wallflowers
Various hair metal bands: Ratt/Poison/Great White/Damn Yankees/Vixen/Winger/Slaughter
The Cure has a great "Unplugged" CD It was a bonus from their Greatest Hits CD. The Greatest Hits DVD is great also. It only has 4 acoustic tracks on it though.
A couple of the SRV tracks are on the 3 disc box set that came out a year or two ago. Otherwise, you'd have to find a boot. I'm sure someone recorded it to vhs and made a cd from it, although I haven't ever come across it myself.
The tracks that are on the box set are very good, a highlight for me.
I know this is an old thread but if anyone pops by to read it you could try Korn's unplugged which is surprisingly good and alsoCD2 of queens of the stone age Era Vulgaris is an astonishing acoustic cd.
Although it's yet to be released (one can only hope) try to check out Vampire Weekend Unplugged on Palladia some time, they sound amazing in this setting with a small orchestra.
If you're a Black Crowes fan, the brothers Robinson put out an acoustic CD (and DVD) of shows they did a few years back. Songs from the Crowes catalog including a bunch of covers and never released stuff. Sounds great!!