My car did the SAME exact thing, headlights and all. Ended up the iginition switch went bad and the pigtails goint to it shorted and melted. Here a link on what to do/check...
http://shbox.com/ignsw/ign_switch_repl.html
Once again shoebox saves the day!

 

Nah, nothing else in the car worked. Dome lights didn't come on when the door was open, horn didn't work.......nothing electric inside the car worked except the headlight switch.

Car was fine again today, BTW.

 

Interesting turn of events.........I was at my sister's today and when I went to leave, it acted like it was gonna start, but then died. I then tried it again, and I got the same results as I got on Thursday the first time it happened. So I opened the hood and wiggled the battery, just like what my dad did to fix it on Thursday. Well, started right up.

I get home, take a second look at it, and after testing the negative and positive terminals, I noticed I was able to move the negative wire with my bare hands......ever so slightly, not using that much force, but still able to nonetheless. Well, I tightened it and it turns out it took a decent amount to tighten it, and the positive wire was able to be tightened also......so I'm thinking this could've been my problem all along, and I just didn't notice it because the wire wasn't THAT loose, but I could definitely see it moving when I tried it with my hands.

So, that's done and I'll have the AC-Delco battery either tonight or tomorrow. So hopefully I'll be set.