ArgoUML is a powerful yet easy-to-use interactive, graphical software
   design environment that supports the design, development and
   documentation of object-oriented software applications.

   If you are familiar with a family of software applications called
   Computer Aided Software Engineering (CASE) tools then you should find
   ArgoUML instantly familiar.

   The users of ArgoUML are software designers & architects, software
   developers, business analysts, systems analysts and other
   professionals involved in the analysis, design and development of
   software applications. Main features:
     * Open standards: XMI, SVG and PGML
     * 100% Java
     * Open Source allows to extend or customize it.
     * Cognitive features like: reflection-in-action, opportunistic
       design, comprehension and problem solving

WWW: http://argouml.tigris.org/