HIDs are illegal iirc if not intended for your lense, mainly due to the fact that they don't refract properly or some such stuff.
What he said. I don't know if a genuine/legal HID setup exists that'll replace a sealed-beam headlight, but my guess is that, given how much longer a true HID setup needs to be, it doesn't.
I know this has been posted many time sbefore (more than once by me), but if you care at all about safety and the people you're sharing the road with,
PLEASE read this!!
As far as sealed-beam replacements are concerned, I'm a big fan of the Euro E-code replacements...you get a better light pattern and can run over-wattage bulbs if your wiring can handle it (i.e. if you've done the relay mod). I don't know how well the OBS projection-style lights work, but they may put out light more efficiently and at a better pattern than the OEM style? Like I said, I'm not sure...and, unfortunately, there's pretty much nothing you can do with a brick nose.
As to the original question, I haven't done much...yet
About the only lighting mod I've done is to add lights to my lumber rack. I eventually want to relay everything, go all LED (except the headlights, of course), and maybe add some flood lights for the rear/sides (for off-roading, the ability to illuminate the area behind the truck for hooking a trailer up at night, etc)...this is the only halfway-decent pic I can find of the truck with the running lights on, and this is from 2005...