Sanger-Bredt Antipodal Bomber
Most people can tell you that the Germans were developing some weird aircraft during the World War II. The German Antipodal Bomber (or Silverbird) was one of these. A revolutionary rocket-powered aircraft, it was designed for supersonic, stratospheric flight capable of striking targets anywhere in the world, that proposed Dr. Eugen Sanger and Irena Bredt in the late 1930s. In 1944 the Antipodal Bomber became one of chosen concepts to bring a "Miracle Weapon" to the USA (it was only one of the Amerika Bomber project). The design was a significant one, as it incorporated new rocket technology and spaceplane concept ideas. In the end, it was considered too complex and expensive to produce. After the war ended, the Sanger-Bredt design formed the basis for major development projects in the 1950-60s (X-20 Dyna-Soar in the US and Keldysh Bomber in the USSR), but these were cancelled.
For more information check out the following sources:
Silbervogel (Wikipedia).
Sanger Amerika Bomber (Luft '46).
Amerika Bomber project by E. Saenger and J. Bredt, August 1944 (PDF).