MUSCLE (Multi User Server Client Linking Environment) is an N-way messaging server and networking API. It includes client-side networking APIs for various languages, including C, C++, C#, Delphi, Java, and Python. MUSCLE lets programs communicate over a network via streams of serialized Message objects. The included server program ("muscled") lets its clients message each other and store information in its server-side hierarchical database. The database supports flexible queries via hierarchical wildcarding, and "live" updates via a subscription mechanism.
Piccolo2D is a toolkit that supports the development of 2D structured graphics programs, in general, and Zoomable User Interfaces (ZUIs), in particular. A ZUI is a new kind of interface that presents a huge canvas of information on a traditional computer display by letting the user smoothly zoom in to get more detailed information and zoom out for an overview. It uses a "scene-graph" model that is common to 3D environments. This means that Piccolo maintains a hierarchical structure of objects and cameras.
OpenSimulator is a multi-platform, multi-user 3D distributed virtual environment platform. Out of the box, it can be used to simulate virtual environments similar to that of Second Life. These can be used as social virtual worlds or for specific applications such as education, training, and visualization. Access is via the regular Second Life open-source viewer or via third-party clients. There are a number of private and public deployments of OpenSimulator, including OSgrid, which has over 8000 regions hosted by independent individuals and organizations spread over the Internet.