I give a lecture in my classes on software engineering called Circles Boxes and Arrows -- and I've given the same lecture for a number of years.  The idea is that there is an isomorphism between virtually all the diagramatic methods since they almost all use some combination of circles, boxes and arrows, adornments and other polygonal thingies to try to capture the essence of software designs in a diagramatic and visually appealing way.

All these methods are helpful but none of them (even UML I suspect) are sufficiently general to cover the space (or span the space as we physicists say).  Thus you always need an EscapeHatch (an interesting pattern there) and few CaseTool''''''s manufacturers have provided adequate EscapeHatch''''''es and that makes their tools less than totally helpful.

It would be helpful to have a textual language which generates in a clear way all the possible circles boxes and arrows and what not in a linguistically clear way -- a tool that I've used that is rather neat in that respect is AllClear which is great at generating flow charts and a few other kinds of charts.

There is also a tool which can be script driven I think called Visio ... I have not used it, although I have a copy, because I'm not a big fan of their user interface.  I keep trying to find the time to learn enough about it to see the range of its applicability.  --RaySchneider
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See also GalacticModelingLanguage