Led Zeppelin - Communication Breakdown b/w Good Times Bad Times
Zep didn't release singles in the UK because it wasn't cool and radio wasn't going to play them anyway. Which reminds me of a famous radio programmer at the time who was asked if he'd play Whole Lotta Love, he responded in the negative. Why? "Because the goddamn singer has an orgasm half way through, that's why!"
Yeah but that's what makes it great, daddio.
Anyway, this was actually scheduled to be released as a single before the band had a change of heart. Rock n roll was being made up day by day, so this sort of thing happened a lot. The single was pulled before it was pressed leaving only a few promo copies out there. These now command £700. Yes. Really. You could buy a house for that when I was a kid.