0 A.D. (pronounced "zero ey-dee") is a cross-platform real-time strategy (RTS) game of ancient warfare. It's a historically-based war/economy game that allows players to relive or rewrite the history of ancient civilizations, each depicted at their peak of economic growth and military prowess.
AShopV provides a shopping cart with digital goods delivery, affiliate tracking, Swoopo-style auctions, full PayPal support, support for many other payment gateways, many shipping calculation options, and multiple languages and currencies. The software also includes a CRM Sales Office with order management where you can create quotes and turn them into bills that can be paid online, set up automatic recurring billing, manage purchase orders, handle customer and vendor contact through POP3 or IMAP, and view customer and vendor history. A Shopping Mall integrates with the affiliate tracking to let you set up your own ClickBank clone.
Abstract provides a basic flow-based accounting model. It supports processing of multiple economic resources. It automatically calculates the value of accounting transactions given information on resource transfers. This also includes automatic revenue recognition and profit/loss calculation on a per-transaction basis.