How to Tether iPhone 4 using HANDYLIGHT without jailbreaking
If you ever wanted to tether your iPhone but found your carriers' prices ridiculously high, then meet HANDYLIGHT. This $0.99 iPhone app has a nice hidden feature. It will allow you to connect to the internet using your iPhone (i.e. tether). There's no guarantee that this app will stay in the app store much longer (or even on your phone after you purchase it), so use it at your own risk.