Clay is a database design tool that runs as a plug-in in the Eclipse (http://www.eclipse.org/) development environment. Clay has an intuitive user interface for graphically designing database models. Clay can also create a database model by reverse engineering an existing database. Furthermore, Clay generates the SQL (DDL) code appropriate for your database.
From joe's Secret Lab comes this interesting tutorial on how to create models in Blender using a "digital clay" method. Those of you interested in alternative methods of modeling will...