One of the most expensive and sought after Coffees in the world is called "Kopi luwak" or Civet Coffee. It's made from Coffee Cherries literally shit out by an Asian Civet. The digestion process causes the beans to ferment making them an extraordinary quality.
Kopi luwak is one of the most expensive coffees in the world, selling for between US$100 and $500 per pound in 2010. The price paid to collectors in the Philippines is closer to US$20 per kilogram. The specialty Vietnamese weasel coffee, which is made by collecting coffee beans eaten by wild civets, is sold at US$500 per kilogram Most customers are Asian, especially those originating from Japan, China and South Korea. Sources vary widely as to annual worldwide production. The price of farmed kopi luwak is considered low-grade by connoisseurs; in large Indonesian supermarkets it costs about US$100 per kilogram, five times the price of a high quality local arabica coffee. (Wikipedia)
Kopi luwak is produced mainly on the islands of Sumatra, Java, Bali and Sulawesi in the Indonesian Archipelago. It is also widely gathered in the forest or produced in the farms in the islands of the Philippines (where the product is called kape motit in the Cordillera region, kapé alamíd in Tagalog areas, and kapé melô or kapé musang in Mindanao island), and in East Timor (where it is called kafé-laku). Weasel coffee is a loose English translation of its Vietnamese name cà phê Chồn, where popular, chemically simulated versions are also produced.
Producers of the coffee beans argue that the process may improve coffee through two mechanisms, selection – civets choosing to eat only certain cherries – and digestion – biological or chemical mechanisms in the animal’s digestive tract altering the composition of the coffee cherries.
During the digestion process, as the cherry moves through the digestive tract of the civet, the skin and pulp are removed, but the beans themselves are not digested. Instead they go through a unique fermentation process.
After roughly a day, the beans emerge in the excreted feces in clumps, usually with the beans still intact (it looks like an unusually disgusting granola bar) and are harvested, washed (thank goodness!), dried, pounded to remove their skins, sorted, and then roasted.