Just helped one of the neighborhood kids load NES emulator onto his iphone. He is not with ATT or T-Mobile. He is with Simple Mobile. Thats news to me. Decent looking prepaid plans/pricing with NO contract. Not sure how good the coverage is, but its worth a try. They currently service over 37 states.
URGE Mobile, LLC (urgemobile.com) does National distribution of Prepaid/No contract UNLIMITED wireless. Located in Brooklyn, New York. They have partnered with T-Mobile.
Another option may be H2O wireless.