Against Me- The Acoustic E.P.
Oasis- The Master Plan
Nirvana's b-sides, mostly their live stuff, is pretty good.
There's a version of Radiohead- High and Dry that uses just stand up bass and piano that's damn awesome

"I'm So Lonesome I Could Cry" - Hank Williams

The B-side to...yes that's right: "There's A Hole In My Bucket"

He thought the imagery in the lyrics would fly over the heads of his target audience. Go figure it ends up being one of the most highly regarded songs in country music as well as in general.

The Mars Volta - B-Sides :D