AgileBill is a Flexible Billing and Invoicing Application for a number of markets, including Web Hosts, ISPs, VoIP Providers, and membership/subscription type models. It features numerious plugins for payment processing, provisioning, and interfacing with a variety of 3rd-party applications and services. Development began as early as 2002, and initially released commercially in 2004. The project was released to open source in November 26, 2008. For a full list of features, see this announcement: http://forum.agileco.com/showthread.php?t=1644 The user community is located at: http://forum.agileco.com