Cheap Prepaid Plan for AT&T IPhone from $3.33/mo
If you have an AT&T - or factory unlocked - IPhone, then Airvoice Wireless offers an extremely cheap prepaid option. If you use a lot of cellular data, then this is probably not the right plan for you. But if you are almost always covered by Wifi, and only need occasional cellular data, then this could save you a lot of money.