Spicebird is your one opensource platform for many collaboration needs. It provides e-mail, calendaring and instant messaging with intuitive integration and unlimited extensibility.
Elmer is an open source multiphysical simulation software developed by CSC. Elmer development was started 1995 in collaboration with Finnish Universities, research institutes and industry.
Clone your pc to another one with this easy to use, Norton Ghost like, and opensource software tool.
The CorneliOS WEBos is an easy to use and cross browser "Web Desktop Environment"