http://en.wikipedia.org/wiki/Bouncing_bomb

I thought this was interesting....

After the raid the Germans discovered an Upkeep bomb that had failed to explode lying in some woods and subsequently a 385 kg (850 pound) version of the bouncing bomb was also attempted by the Luftwaffe. Designed for use against British shipping, it was given the codename Kurt, and was built at the Luftwaffe Experimental Centre in Travemünde. In trials, dropped by an Fw 190 it proved to be dangerous to the delivering planes as the bomb matched the speed at which it was dropped. Attempts to rectify this with booster rockets were ultimately a failure, and the project was discontinued in 1944.

__________________