My buddy at Redfin, Glenn Kelman, decided he wanted to bare his financial soul so that other entrepreneurs could get greater insight into the witchcraft called financial modeling. In this two-part posting, he reveals his numbers and his lessons. They are eye-opening for most entrepreneurs.

This is a guest posting by Glenn Kelman, CEO of Redfin, a company that enables people to buy homes online. He offers a counterpoint to my posting about how easy it is to make millions of dollars with "user-generated, long-tail, Web 2.0, social-networking, open-source content" - sites that can be started and run by people sitting at home tapping away on their computer in their underwear.