I'd give these guys a call:
I've dealt with them once before on an HID conversion and they were very helpful. They have a good reputation for quality and knowledge, and they'll help you choose over the phone if you want.
You're probably looking for an HID driving light. HID lights are bright, clear light with an incredible throw - I have a single 35W HID as my motorcycle headlight, and it lights up the road better than 99% of the cars out there. It just throws a solid blanket of light over the road!! Mine was just a cheap conversion into the stock headlight housing, too - that'll work most times if you have projector style headlamps. Won't work with reflector-type housings.
Driving lights have about a 10-15 degree spread and should go out front pretty far. Pencil beams are more narrow, will go farther, but won't light up the shoulder.
Something like the Hella Rallye 4000 would put out a ton of light. You'd have to be very careful when running them on open roads - I can't speak as to whether that's legal or not. Either way, aim them carefully, these things'll blind oncoming cars.
(Just saw your post about HIDs - stock HIDS or a well-done conversion will blind oncoming traffic *less* than regular incandescent bulbs. It's conversions into reflector housings and poorly-aimed lights that are the culprit.)