Ask 37signals: How do you process credit cards? - (37signals)
http://www.37signals.com/svn/posts/753-ask-37signals-how-do-you-process-credit-cards useful article and (especially!) comments about ecommerce systems
http://www.37signals.com/svn/posts/753-ask-37signals-how-do-you-process-credit-cards useful article and (especially!) comments about ecommerce systems