Rear end squeak

I recently developed a squeak when turning right--at first I thought it was my brand-new front wheel bearing which I bought off e-bay. Luckliy, though, the noise is actually coming from the back. If I push up and down on the back bumper I can hear it, but I can't for the life of me pinpoint it and the shotgun greasing approach has yet to weild fruition. Amazingly there's not much previous discussion on rear-end squeaks, so I'm hoping I can get a list of things that might cause me to get a bed-spring like squeak from the back both while moving and turning and while stationary and bouncing up and down.

Okay, with the help of a friend with better hearing than my own I've discovered that it's the parking brake that's making the noise. I'll pull it all apart during my next rotation and see exactly what's going on...