A failed Magic: The Gathering card trading site becomes the birthplace of Bitcoin's first real market.

Programmer Jed McCaleb had bought the domain mtgox.com back in 2007 to trade Magic: The Gathering Online cards, abandoned it after a few months, then let it sit idle. In the summer of 2010 he stumbled across Bitcoin on Slashdot and realized the young currency needed somewhere people could actually trade it against dollars. He repurposed his spare domain, wrote the exchange code himself, and on July 18, 2010, posted to the Bitcointalk forum. "Hi Everyone, I just put up a new bitcoin exchange," he wrote. "Please let me know what you think."

On its first day, Mt. Gox traded just 20 bitcoins, at five cents apiece. I love that a site which would eventually handle 70 percent of world Bitcoin trading opened with less money than a fast food lunch.

McCaleb sold the exchange less than a year later to Mark Karpelès, and everyone knows how that story ends. But for one afternoon in 2010, it was just a guy with a spare domain nobody had touched.

That's today in crypto history. See you tomorrow.