rear end noise

I have a 2000 GT and about a month ago I started getting a noise in the rear end. I thought it was rubbing against the wheel well, I pulled it back and still the noise is there. It only makes the noise when driving and gets worse the more weight there is in the car. Any ideas?

Have you jacked your car up in the back with a floor jack or something recently.. I've seen things get bent by improper positioning of jacks, that caused noises..

Can you describe the noise a little more? Is it a rubbing? A clunk? A ?

Also, when does it seem to happen. Going over bumps? Turning?

The Burning Rom- The noise sounds like rubbing, not sure if it is or not because I can't see were it might be rubbing. It happens all the time when the car is moving, gets louder with the more weight there is in the car. It is worse when turning right than left, which makes me think it's on the left side.
GTPJeff- no I haven't jacked it up, had it on a ramp to find rubbing, that's it.