Is this a V6 or a 4 cyl??? What year? From your ID, I'll guess it's a V6. Does the noise happen all the time, when idling, accelerating, standing still, AC on or off?? C'mon, throw us a bone here...
The serpentine belt is on the passenger side near the fenderwell. Open the hood and see if the sound is coming from there. Does the sound change with engine speed? When mine did this, it turned out to be the pre-cats had crumbled and were rattling around inside the exhaust. Not saying this is what you have, but that noise could be lots of different things...
