Here are a few, and no I'm not a huge grunge fan, but the Unplugged CDs are extremely well recorded:
Supertramp Crime of the Century
Supertramp Even in the Quietest Moments
Stone Temple Pilots MTV Unplugged
Alice In Chains MTV Unplugged
Nirvana MTV Unplugged
Natalie Merchant MTV Unplugged
Memoirs of a Geisha Soundtrack