Check the swaybar endlinks on the rear - if they're loose or broken they may make noise, and it's an easy fix.
Jack up the car & start shaking stuff, see if you can pinpoint or even get a general idea of where the noise is coming from. There's a good number of points to check:
Sway bar end links
Inboard sway bar mount bushings
Lateral link bushings (inner & outer, front & rear)
Trailing arm bushings
Upper Strut mounts
Spring isolators on the shocks
The struts themselves may be shot too, but I'm not sure they'd make a noise
