I have two minivans that had clouded headlights: 1994 Caravan 1999 Voyager
After a lot of research I decided to try the little kit sold at SOME Walmarts (but mine didn't have it at the time, so I bought at Advance Auto Parts in Sept. 2006 for less than $20, if I recall. http://www.crystalviewchemicals.com/index.htm
I did the 1994 Carvavan first. It was a bit messy, but fairly easy to use (although I think the printed instructions had an error about which sandpaper to use first---you need to use the coarser sandpaper first---I think they were color coded and the instructions had the colors wrong, IIRC). It took about an hour or so to do.
As I went through the process, I wasn't optimistic, but when you put the final clear liquid on the lens, PRESTO....amazing: cloudy becomes crystal clear. I mean, it was really great.
This clarity lasted for a year, and now the lenses are cloudy again (not QUITE as cloudy as before, but not good).
This same product was totally worthless on the 1999 Voyager which has the newer curved type of headlight assembly. On that one, the damage to the lenses was not predominantlysurface damage, but deep within the formerly clear plastic, and perhaps INSIDE the assembly too. A few months ago, it got so bad that I shopped online and got a pair of new ones for $169. (I still need to align them, and I've asked for advice on this NG, but I don't think there's been a reply.)
Anyway, I'm probably going to see if the kit manufacturer will honor their warranty and send me a new kit so I can redo the 1994 van.