A real pain in the ass during WWII was the enemy constantly trying to not get bombed. Ways of jamming guidance systems for homing missiles meant a lot of targets went unblown up, so effort was put into finding a way to guide a missile that couldn't be jammed.
Every psych 101 students' favorite sleep aid, BF Skinner, proposed the idea of using pigeons. Put a pigeon in a bomb and have the target displayed on screen for it. The pigeon would constantly correct the course by pecking on the image of the target in the center of the screen. Jam that, Nazi assholes.
What went wrong:
Even though a chunk of change had been dropped on the project, the military abandoned it. Some say it was just too weird for them, while the time involved in training the pigeons had also been cited. One of the problems was the range of the weapons, as they relied on an optical system, since the pigeons had to see what they were pecking at. If the bomb went too far off course, the pigeons would have to correct for themselves and the bomb. Another problem was that it was a bomb guided by a fucking bird.
7The Sun Gun
Destroying your enemies from space is the goal of every angry 4th grader and Scientologist. Unbeknownst to many, it was also the goal of the Nazis, who figured a space station/death ray combo would have been gangbusters.
Appropriating the work of less genocidal minds, Nazi physicists began work on an idea that would put a giant mirror in orbit. The mirror, which they planned to design from about one million tons of metallic sodium, would burn cities to the ground, boil reservoirs, crisp people like bacon and probably make all kinds of kids with magnifying glasses huddled over ant hills feel grossly inadequate.
The mirror would be on a space station manned by Nazi spacemen with magnetic boots to help overcome weightlessness, with oxygen provided by on-board pumpkin patches and electricity provided by solar powered steam dynamos. The cafeteria would presumably have food deep fried in love and the rec room would be structured out of the dreams of children and unicorn gonads.
What went wrong:
We did. "We" being all the non-Nazi assholes, the more colloquial name for the Allied forces. When it became clear that we were going to win the war, the US began taking German scientists out of the country and this plan, along with many others, was abandoned. Also, the epic, grand scale, and mind-bogglingly retarded nature of the entire idea was apparently a roadblock that needed to be overcome too, since we couldn't even build the damned thing now, in 2008, if we wanted to.
And trust us, we want to.