I used the wife's hair dryer and a screwdriver on my fog light... I tried to heat the housing rather than the lens to avoid warping it, worked slowly and as evenly as possible, took a while but managed to get there with minimal damage!
I did read somewhere about putting them in the oven to heat up the glue as a quicker method but wasn't brave enough to attempt it, plus the wife would probably have me sectioned if she caught me baking car parts in the oven!
