Want your Web App to store credit card data? Use monkeycharger.

THIS HAS BEEN MOVED TO http://github.com/joevandyk/monkeycharger

Store credit cards via the REST api. Then, you can authorize and capture amounts on those stored cards (or do one-time authorizations/captures on a non-saved card). Uses ActiveMerchant for authorizing and capturing.

Credit card numbers are stored in the database. As such, you'll want to run this application on a very secure machine. When saving the credit card, you'll need to supply a unique key (I call it "passphrase"). You'll need to use the correct passphrase when authorizing a saved card.