A.I.M. - Or Advanced Idea Mechanics. When ever a hero busts an A.I.M. operation up hilarity always ensues because it comes down to heroes versus scientists, who love bringing up the fact that they are just scientists and cannot be expected to defend themselves from the likes of Captain America, or which ever hero happens to be laying down the pain.
It also doesn't hurt that they are lead, generally, by M.O.D.O.K. (Mobile Organism Designed Only for Killing), a giant floating head in a mechanical body. Seeing mindless yellow suits beat to a pulp by heroes always brings a smile to my face.