Just been listening to a few B-sides from Pixies and Nirvana (and Smashing Pumpkins).
Here's a good list - and these kind of tracks never get mentioned!
Velvety Instrumental Version - annoying yet addictive
Wave of Mutilation (UK Surf)
River Euphrates - the B-side version has that extra kick
I've Been Waiting for You (neat Neil Young cover - great intro riff)
These tracks are pretty underrated:
Oh The Guilt
Even In His Youth - the bridge is the coolest part ("He was born for your crew...")
That's enough for one day I reckon. Shame most bands don't do B-sides anymore :/