I think I remember reading something about Soviet mice trained to eat at German tank wiring.

I also remember a History Channel show telling about a Pigeon-Guided bomb. The bomb would contain a pigeon which was trained to peck at a picture of a battleship. Once dropped, the guidance mechanisms would interpret the location of the pigeon's pecking and would steer the bomb accordingly. This did not make it into production.

I may have also read about foxes covered with luminous paint dropped into Japan as a method of frightening the population.