Up for grabs on eBay is an Apollo 11 signed first day cover by Astronaut Neil Armstrong.
The seller says, "This is an Apollo 11 Manned Lunar Landing - Pacific US Navy Recovery Force first day issue cover/envelope. This wonderful old piece has a great, vintage design...canceled on July 24, 1969, onboard recovery ship USS Hornet. Hand-Signed by Astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins. [It is] from the estate collection of Charles D. Clary."
Charles D. Clary was a long-time employee of NASA and other space-related endeavors--totaling more than 51 years. He was the man who actually put Astronaut Ape's/Monkey's Ham and Ines into their Mercury Space Capsules, according to the seller's description.