TwitterHawk can help you do market yourself or your product on Twitter to people unknowingly interested in what you have to offer by means of targeted marketing.

Spokeo finds information about your friends—long-lost or not—and then tracks their online activities as they make updates.

Glenn Kelman [at Redfin], 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.