Everyone likes money because of the value it has in itself. Coin collectors like certain kinds of money because of rarity or historical value. Every once in a while, currency comes around that is just plain fun.
In 2007 the nation of Mongolia chose to honor US President John F. Kennedy because of his role in the creation of the Peace Corps. The government produced a limited edition ₮500 coin (five hundred Tugrik is worth approximately 20¢ in US dollars) with JFK’s image and a tiny button that, when pressed, plays a recording of Kennedy’s famous “Ich bin ein Berliner” speech.
The next year the Pacific island nation of Palau chose to honor the 150th anniversary of the apparitions of the Virgin Mary at Lourdes with a special edition silver dollar. Each of the dollars contains a tiny vial of holy water from Lourdes, France.