An American Express Serve app for both Android and iOS has been created for online purchases, paying bills and even person-to-person payments. The master account holder can create sub-accounts with spending limits—good for children, for example.

There'll also be an actual debit card issued for the main user too, so it's not all done digitally. Unfortunately—as with most things in life—it doesn't come free:

Highly Competitive Fees Waived for Launch
Serve consumer fees will be highly competitive. There are only two fees for consumers and we are waiving the fee to put money into the Serve account for the next six (6) months. The two fees are:

Putting money into a Serve account: 2.9% + 30c/per load, discounted to 0% for cash, debit and ACH.
ATM cash withdrawal (after first one each month free): $2.00
Unlike some other products in the market, Serve has no fees to open an account, no monthly fees, no fees for P2P transactions, no fees to set up sub-accounts (up to four accounts) and no fees to use the widgets.

The widgets it refers to are for supporting charities. They can be downloaded on Facebook or put on personal websites to ask for donations—but in the future, American Express Serve will let people make their own widgets so they can sell stuff, too.

The service and apps are available in the US today, and will launch around the world later this year. [BusinessWire via SlashGear]