Gobby is a collaborative editor that supports multiple documents in one session and multi-user chat. This means that it gives you the ability to edit files simultaneously with other users over the network.

Dia is a program for creating diagrams, graphs, flowcharts, etc.
There is support for UML static structure diagrams (class diagrams), relationship diagrams, electronic elements, flow diagrams, network diagrams and many others.
Dia includes a large number of graphic elements for drawing various diagrams: block diagrams, electrical diagrams, chemistry, Cisco and others.
Diagrams are saved in XML format (additionally compressed using gzip), and export to JPEG, EPS, SVG, XFIG, WMF, PNG and other formats is also supported. You can import new objects into Dia, which are described in XML files.
Dia is extensible with new sets of objects that are described using files in an XML-based format.