Internal engine coatings?

Does anyone use those fancy coatings, like the anti-friction coatings on the sides of pistols, ceramic on piston tops/combustion chamber, oil shedding coatings, etc.?

I'm thinking I'll do some sort of ceramic/exhaust coating on my manifolds, maybe trying some different ones on my valves and pistons... Anyone have any opinion on these? Fancy hooplah to steal your money or is there some decent benefits for the money?