In 1993, Jennifer Toth horrified the world with her book The Mole People: Life in the Tunnels Beneath New York City. The work detailed the lives of the homeless citizens who’d established communities in the subway and railroad tunnels beneath the streets of New York. Though criticism of the validity of some of Toth’s claims ran rampant following her book’s release, over the years various other sources have indeed found many people—one documentary estimated as many as 6,000—living illegally and dangerously in the subway tunnels.
A clarification: while new media entrepreneur Jakob Lodwick did indeed invent the term "norbum," a portmanteau of "Nordstrom" and, well, "bum," then "register a few domains," he was not, specifically, one of the people involved in the homeless people-mocking site that then went up at norbum.org. Lodwick helpfully adds that he still reserves the right to make fun of homeless people in the future. [JakobLodwick.com, Valleywag]