How to fix a headlight...

So my headlight went out on the passenger side, just the main headlight (brights still work and foglights works.) Came back on the other night, then went out again, so I hit it and now it's stayed on...any suggestions as to what would be causing it? Bad ground/wire/whatever the heck you want to call it, maybe? And how can I fix it if it's not the bulb itself?

That is weird .. but my vote is still for a bad bulb. Switch the Pass. for the Drv. side and see what happens?

Bad bulb. One of the filaments is bad. When you tap on it, it made a connection and "arc welded" itself together. Change the pair and keep the one good one as an emergency replacement. And you might already know this, but handle the bulb with a glove or rag, fingerprint oil will make it fail sooner.

I have a foglight that operates like that but my problem is corroded electrical contacts. Just remove the flaky bulb and examine it carefully, it could easily be a blown filament too.

Bad bulb... I have had that happen many times.

x2 on bad bulbs. The bulbs also do loose intensity over a few years (some don't last that long) I would go invest in a good pair of PIAA extreme White 9007's
http://s779.photobucket.com/albums/yy75/LibertyTC/Jeep%20Liberty%202004/?action=view&current=PiaaBulbs2.jpg
I took one of my old stock bulbs, and wrapped it in a bubble pack and store it in the Jeep for a spare, as emergency replacement.
Especially in winter, inspect all of your bulb plastic housing enclosures for moisture accumulating on the inside. This is a sign of a crack or worn seals in the housing. Moisture is not good for bulbs and connectors.

When you are replacing the bulb(s) take the time to check the pin openings in the connector - if there is some brown discoloration in the plastic that would indicate some overheating and you might need to replace one or both connectors. Most auto parts stores will carry replacements, just make sure it will fit the 9007 bulbs that the Jeep uses.