Here we go! Here's mine.
Ray Sphere: When thrown it blows up and sucks a little AP from anyone near it to where it landed, making a nice neat pile for anyone to take. (Infamous)
Little Sister Adam harvester: One hit only, but when it hits someone it makes them walk slowly and slowly drop AP, think of the speed as in between the missile and normal (Bioshock)
Worker cap: Goes on your head and gives you three 3-second bombs to place (Fat Princess)