* The 1908 Zeppelin Airship Stamp (Germany): This stamp was issued to commemorate the first flight of the Zeppelin airship LZ 1. It is considered to be one of the most valuable stamps in the world, with only about 150 known copies.
* The 1929 Graf Zeppelin Stamp (Germany): This stamp was issued to commemorate the first round-the-world flight by the Zeppelin airship LZ 127 Graf Zeppelin. It is also a valuable stamp, with only about 1,500 known copies.
* The 1933 Hindenburg Stamp (Germany): This stamp was issued to commemorate the first flight of the Zeppelin airship LZ 129 Hindenburg. It is not as rare as the previous two stamps, but it is still considered to be a valuable stamp, with only about 10,000 known copies.
These three stamps are all considered to be great investments for stamp collectors, as they are all rare and valuable.