According to Forbes, the website Silk Road, which functions as an anonymous on-line marketplace for buying and selling illegal drugs, is going through a bit of a boom.
Annual Sales passed $22 million. Well, the equivalent of $22 million, that is, because the only valid currency on Silk Road is not dollars. To some degree, the currency doesn’t actually exist at all.
Buying and selling on Silk Road requires the transfer of the virtual and very tough to track Bitcoins.
This, couple with the fact that Silk Road uses the Tor hidden service, means that people using the site to buy or sell illegal drugs can do so without fear of being unmasked, as it were, by the authorities.
Forbes cites a study by Nicolas Christin, which can be found here.