https://stripe.com/
Payment API built for developers to process credit cards. One can even process payments via curl!
http://visionwiz.net/2010/01/you-can-use-paypal-account-anonymously/
Simple article on how to set up a PayPal account that is not easily or directly linked to a person's name.
http://www.blackhatworld.com/blackhat-seo/making-money/142412-how-setup-anonymous-untraceable-paypal-account.html
Vaguely illegal sounding article on how to use PayPal anonymously. Involves gift card based activation, a clean IP, and an anonymous card that can be used as a bank account. US specific.
http://www.owjo.com/
Sell on facebook and other places. They handle everything for 7% plus 3% + 30c for card processing, but they'll take cards for you, no merchant account required, through elavon.
