Bitcoin values plunged and then mostly recovered today after the U.S. government closed the Silk Road Web site, where Bitcoin had been used for trading in illegal products.
Those who know little about Edwin Walter Kemmerer (1875-1945), in Brad's post below, should be aware that although he left no lasting contribution to economic theory that I can name, he was quite prominent during in the interwar period. He was the most influential "monetary doctor" ever, leading teams to reform the monetary, banking, and fiscal systems of Bolivia, Colombia, Chile, China, Ecuador, Guatemala, Peru, Poland, South Africa, and maybe some other countries besides, as well as being on the Dawes Commission that restructured Germany's post-World War I debt. His typical approach was to bring, or restore, the gold standard by replacing whatever monetary arrangements had previously existed with a central bank of the kind that was considered orthodox at the time. He was critical of the Bretton Woods system because he understood that it was more weakly tied to gold than preceding international gold standards.
There is a good book on Kemmerer's South American work called The Monetary Doctor in the Andes. His son Donald, who was also an economist, wrote a biographical sketch of his father, but the father merits a full-scale biography. The son accompanied the father on some trips, and he relates about a trip to Paraguay that the family was on a steamboat heading upstream from Buenos Aires when the boat struck a rock and sank. The Kemmerers were strong swimmers and survived, while some other passengers did not.