If you have factory fog lights you may notice that they only work when you have your low-beams on. They can't operate with the parking lights alone, nor do they operate when you switch to high-beams. The wiring behind the dash trim can easily be altered to allow the fog lights to be on with the parking lights and high beams, or completely independently from the headlight system. Advantages to having the fog lights on without the headlights are that you can see under dust and fog more effectively with the lower-mounted lights, and you can easily light up a wide area without burning all your lights (e.g. pitching a tent in the dark). This setup can also make a good daytime light system.
 
You will need to remove the dash trim to access the wiring behind the switch. take out the two 7mm bolts holding the ash tray in, then the rest of the trim piece just snaps off.
 
I did this on a '94 Ranger. Other years may or may not be similar. It's up to you to explore and do some multimeter tests to see.