ShareJS is an Operational Transform library for NodeJS & browsers. It lets you easily do live concurrent editing in your app.
What is the Locker Project? A Locker gives people ownership over their personal data and clear control over how it's protected and shared. Providing flexible APIs for access to that data, Lockers are a powerful way for developers to build applications that leverage rich personal data.
The Distributed Reporting Toolkit (diretto) project offers an open source solution for distributed on-site media reporting and collaborative event coverage in realtime. The platform provides a scalable and highly modularized infrastructure that is easy to extend and to customize.