It would work on the headlights also. For those I would tint the inside to precent rock chips from pitting it up. If you have a plastic lensed headlight it would not matter though. With that the VHT really has some issues with laying out thin. I would go tinted clear coat for sure on the headlights.
Here are a few other MISC write ups:
Reference
The waste oil burner one is fun. Melt steel in your back yard :P
Most of these are Volvo specific but some are not:
Modifications