Additives

What do you guys think of the zillions of fuel/oil additives being sold of the shelf. Do they really do what they're adverised they would do? or it's just a rip-off?

Some work, others are a joke. Like the lucas oil additives are pretty good, most of the injector cleaners aren't bad. All the Seafoam products are good stuff. But most of that crap is just that, crap.