Unusual inventions that worked during the war

Which unusual World War II era inventions successfully did what they were designed to do?

Hobart's Funnies and French frontier fortifications are defended as successful in their intended roles. Early fusion research is also recalled, with its details left uncertain.

Hobart's specialized armoured vehicles are offered as a successful family of unusual inventions. French frontier fortifications are defended as effective against direct attack along the border they covered; the route through Belgium involved a different political and geographical problem. An early fusion idea is recalled in connection with Teller and an indistinct collaborator in 1944. The transistor is suggested as a possible favourite, then set aside because it is not considered odd. Successful performance of an intended task and unusual appearance or design remain separate criteria.