Problem; I have a hunch it's heat related
 

I park my 03' 350z in the sun after driving for a solid hour; Come back and Speedo, Tach, Oil Temp, all read 0. My handbrake light, "Slip" light, "TCS: Off" light, and blinkers don't light up or make noise on the dash, but DO work outside of the vehicle. Tail lights dont work but brake lights do. Headlights are stuck on. This happened once before, but I just let it sit overnight after disconnecting and reconnecting the battery. It worked fine the next morning.

Any ideas?

So it sounds like a problem with your gauge cluster if I'm reading your statement right. You're saying once you restart it, even your tach reads 0 rpm?

I suspect your gauge cluster wiring loom is not connected properly. I would look up where the plug is and double check the connection. Also, I would search to see if there is any way to check the gauge cluster itself, since it seems to be exhibiting the problem. Search to see if there's an ohms test you can do with a multimeter.