You seem to have forgotten about or overlooked Autodia and other free software that already does this.
Perl has several GraphViz modules for diagramming databases, classes, etc
There are also dozens of perl (and other) scripts to generate diagrams from sql, etc in anything from dot to dia.
..and of course there is Autodia which has been able to draw class diagrams (in dot, dia and other forms) from python, perl, php, c++, Java, SQL and other sources for quite some time.
NB I am the author of AutoDia and maintainer of a graphviz module. But if Michele can plug python warez, I'll plug perl stuff ;)