David, thank you very much.
There is actually a programm for postgres that does that automatically. It creates an ER diagram from the database schema:
http://www.rbt.ca/autodoc/
Autodoc can export to html, docbook, dia and vizgraph (supports ps, gif, jpeg, vrml, png.......).
You can see a complete database of my OpenACS/dotLRN 2.0.3 installation here:
HTML: http://dotlrn.uni-mannheim.de/doc/schema/unima1.html
JPEG: http://dotlrn.uni-mannheim.de/doc/schema/unima1.jpg
PNG: http://dotlrn.uni-mannheim.de/doc/schema/unima1.png
GNU-DIA: http://dotlrn.uni-mannheim.de/doc/schema/unima1.dia
GRAPHIZ:http://dotlrn.uni-mannheim.de/doc/schema/unima1.dot
XML:http://dotlrn.uni-mannheim.de/doc/schema/unima1.xml
VRML:http://dotlrn.uni-mannheim.de/doc/schema/vrml/unima1.vrml
We could extend somehow the documentation package to autocreate the database model for all installed packages.
I have no idea if there is anything similar for Oracle. But I bet there is.
Greetings,
Nima