Python Hyperschema
Python Hyperschema is an open source public domain project that creates useful and really cool HTML hypermaps from SQL database schema, consisting of two small PL/SQL files and one Python (or C) source code file. The generated HTML pages have mousover data displays for all foreign keys, hyperlinked to the foreign key tables, as well as a hyperlinked list of all foreign keys pointing to each table and a master index of all tables.