via Forbes.com...
A few simple tools can get you information once available only to private investigators and police.
In May Matthew Smith received a piece of junk e-mail from a marketer. The marketer chose the wrong guy to spam.
Smith, a pseudonym, is a former hacker and now works as a network security engineer. He runs a blog called Attack Vector devoted to online security issues. He decided to use the marketer, named Steve, as his guinea pig to show how easy it is to track down information about someone based solely on an e-mail address, and documented how he did it to serve as a warning to others who may not understand the power of what's available to anyone looking to dig into your background. (more)
