You know those ads in the back of your newspaper, or alt-weekly... "Hospital X needs healthy volunteers to participate in a research study of vision....Payment is $25 per hour and a session will last up to 2 hours." Fifty bucks isn't much... but some research studies and clinical trials will pay thousands of dollars for human lab rats. The result is a burgeoning subculture of people making a living from these trials. It's lucrative, but risky— we'll talk to the author of an extensive article in Wired magazine about it, as well as a "drug test cowboy." Have you ever participated in a test study? Would you?