Dia is a GTK+ based diagram creation program for Linux, Unix and Windows released under the GPL license. Dia is inspired by the commercial Windows program 'Visio', though more geared towards informal diagrams for casual use. It is an editor for diagrams, graphs, charts etc. There is support for UML static structure diagrams (class diagrams), Entity-Relationship diagrams, network diagrams and much more. Diagrams can be exported to postscript and many other formats. To install DIA try >sudo apt-get install dia. for more information on Dia follow the links below : Link 1: https://help.ubuntu.com/community/Dia Link 2: http://live.gnome.org/Dia Link 3: http://www.gnome.org/projects/dia/ Dia for windows : Link 4: http://dia-installer.de/index_en.html Tutorials and documentation Dia Tutorial Dia tutorial written by Harry George Dia documentation A chapter about Dia from the book "The GNU/Linux Desktop" by Kayon Toga Dia/UML Tutorial A nic...