If you have a stabilizer bar look at the link rods for the stabilizer bar. Most of the time little rattles over bumps are the little ball joints in the stabilzer bars. Cheap fix if thats the deal. You could disconnect them and drive it see if the noise changes,.

 

+1 Check your sway bars!

You can remove the shock and see if they are shot.

 

Thought I'd chime in and say that 3 weeks ago I heard a loud bang and after that I heard a sound like a bolt rattling around when I hit bumps and sometimes when I reved it and it turns out my starter had loosened up enough to move into the ring gear while I was driving and it busted the nose cove off and it was rattling around in the bell housing.