By far the most popular (and most versatile) plugin for working with payment gateways from rails is ActiveMerchant. I’ve used it in a couple of places, and it’s been a joy to work with, apart from one slip-up which was largely due to inadequate documentation. So I’m very pleased to note that they’ve release their 1.0 and launched a website, which bodes well for improved documentation and support.
Tags: activemerchant, credit card processing, payment gateway, plugins, ruby on rails