i've been having similar problems. My tail lights, marker lights in the front, license plate lights, and instrument cluster lights had all gone out. I was told to check a certain fuse under the hood. I checked it and found it blown out, and replaced it. I put in a new fuse, same size, and everything started working again. Then the new fuse blew out. I put in a second fuse and again everything is working. Still, I am concerned about what is causing the short in the first place.
After reading this thread I am thinking my problem is the radio/stereo headset that I messed the wiring up on. I had it professionally installed, but messed the wring up myself. Long story. How that is connected to all that other stuff is beyond my limited comprehension. Electrical troubleshooting is some tricky stuff. I feel certain that is where my problem starts though. Thanks for the tip.