1997 2.2L Cavalier Coupe

A While ago I found out that my battery was draining while the car was sitting off. I pined the problem down to something that is run through the Interior Light fuse. Now that it is nice outside again id like to track down the short so I can have my stereo and interior lights back.

I used a multi-meter to check the voltage when doors were open even with the light bulb removed and I got no significant change in voltage. I disconnected the stereo with the fuse still in and got no significant change in voltage. It seems like every interior light including the trunk light seems to make no difference to the voltage while the car is off. There is STILL SOMETHING drawing a small amount of power constantly that runs through that fuse but it is still enough to kill the battery when you leave the car overnight.

Has anyone got an idea? Maybe someone with a similar problem?