If you want tether your iPhone to your computer to share its 3G connection, you have to pony up $20 a month to AT&T for the privilege. Unless you're 15-year-old Nick Lee, who snuck an app that could do it for free into the App Store under the guise of a simple flashlight app.
Handy Light, which has since been removed from the store, was a $0.99 app that looked just like a slew of other garbage flashlight apps cluttering up the App Store. It's main functionality appeared to just be changing the screen to different colors.
Unfortunately, Apple was clued into the trick once people started talking about the app online. But for those lucky enough to snag it before then can keep enjoying the free hotspot ability as long as they want.