Feature Diagrams modeling tool (Now with FD Complexity information). This plugin also allows UML2Tools Class diagram elements assign to Features elements. From this assignment You can configure Your system and create new UML class diagrams.
XCDE (eXtreme Collaborative Development Environment) is a plugin for Eclipse that adds support for real-time collaborative editing over the Internet, letting developers work on the same files at the same time from up to halfway around the world.
An EclipsePlugin to achieve distributed pair programming on the internet, it is based on open sourced Syncshare server. This plugin will finally make XP possible b/w distributed teams.