A software-based online payment system
Bitcoin is a decentralized P2P electronic cash system without a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of the network to check for double-spending.
Hotel property management system
HotelDruid is a property management system (PMS) designed to make hotel and hostel rooms, bed and breakfast apartments, or any other kind of daily rental easy to manage from a web browser.
mojoPortal is an accessible, compliant, extensible, cross platform, cross database, content management system CMS written in C# ASP.NET. If you know how to make an ASP.NET UserControl then you already know how to make a feature that plugs into mojoPortal