Just read an interesting article in the Numismatist titled "Money of the Gods" by Robert D. Leonard, Jr. The article talks all about the use of cacao as money from the Mayan and Aztec times until the 1940s and perhaps even later. One thing from the article that I had never heard before and found very interesting was that cacao beans were so valuable that they were actually counterfeited. "In 1535 Gonzalo Fernandez de Oviedo y Valdes described how the heart of the bean, containing the nibs, was cleaned out through a tiny hole and the hollow shell packed with earth."
Interesting.