There are many different forms of payments for both off and online transaction. To accept payments online in an automated fashion and speedy a payment processor must be setup and integrated. Depending on the different platform (software) you are putting both virtual and physical products up for sale on will depend on the integrations and payment processors that are available.
There are many content management systems available (CMS) from simple Wordpress sites with to full on ecommerce software. All of these will need some sort of payment processor or gateway.
The most common of payment processors are as below, if you would like another listed please get in contact with @krumz or @Stormy on the #wiki channel at http://slack.ionomy.com and we will review and update this list.
Payment Processor services
There is a dedicated ion payment gateway being built at the moment, more details to follow.
Product and listing software
Wordpress 'Woo commerce' - available as an easily downloadable plugin for very quick setup and selling of products.
Wordpress - Download Here
bbPress - Download Here
PaidMembershipsPro - Download Here
easydigitaldownloads - Download Here
wpmudev - Download Here
WP-Commerce - Download Here
JigoShop - Download Here
AppThemes - Download Here