If it does nothing at all when you turn the key there are a few possibilities. There is a fuse under the hood that could be blown, a bad ignition relay, or a bad ignition switch. I don't remember what the label is on the fuse, but it's one of the big maxi fuses(40 amp IIRC). My car would blow this fuse randomly, and when it does nothing happens when you turn the key. My starter signal wire was resting on the header causing the fuse to blow, but after replacing the fuse it would sometimes go a couple weeks before blowing again.

 

Check your gauge fuse inside of the drivers door panel. My Z28 did this same thing and I pulled the gauge fuse replaced it and fired right up. Just a thought.

 

After replacing the ign switch, it still wouldn't do anything. Then we come to find it was blowing the fuse that Jimmy was talkin about a few posts up (Thanks Jimmy, 50 amp "ign" fuse btw.) We have successfully traced the short to the starter wire but we haven't been able to jack it up and see what's up yet. gonna check in the mornin