I've been searching for something similar for along time. Just hook up a database, and et voila you can see it, modify and export it with a clean and fast interface.  Among the many (really a lot) features you have: 

• Database Browser: Tree based navigation through all database objects. Browse object details and invoke management features
• Database Object Management: Visual support to create, alter and modify characteristics for database objects such as tables. Edit and compile support for procedures, functions, packages and triggers. Extensive database specific support.
• Table Data Management : Support for editing table data including binary/BLOB and CLOB data types, import from file
• SQL Tools: SQL editor with support for auto completion, parameterized SQLs, SQL formatter, visual query builder, explain plan, export large result sets
• Database Server Management: DBA features for managing database instance, storage and security parameters in the database server
• Tools : Export objects in a database/schema as DDL and table data
• Comprehensive Database & OS Support: Oracle, Sybase, SQL Server, PostgreSQL, DB2, Mimer, Neoview, MySQL, Informix, JavaDB/Derby, Windows, Mac OS X, Linux/UNIX

However, to me the most important thing is that the visualization algorithm works really well! You can also choose how to layout the tables in your DB (hierarchic, organic, orthogonal, circular). Oh yes and there's a *free* version of it!!! (Installing DbVisualizer and running it out of the box automatically launches the DbVisualizer Free edition, not as many features as the full version, but still very useful!)