I'll have to check out the Heet myself. I've seen it around, but never tried it...didn't know it dated back that far.
While it doesn't work for me, several people I know (including Watson) love DMSO as a mild pain reliever. It works for her on some pains when all else fails (even medications).
It frightens a lot of folks, though, because it's a laboratory solvent that penetrates quickly, no one really knows why it works, and makes some folks taste garlic as soon as it touches your skin. There's some intuitive wisdom that will say "that can't be good for you."
So far, however, no laboratory tests have found any negative effects (unless you count garlic taste). Since I don't use it, take my endorsement with a grain of salt, but I follow the data.