Umlet-erd contains The essential tools to create erd diagram
its integrated with Umlet (http://www.umlet.com/)
you should download Umlet first before adding this tool from this link 'http://www.umlet.com/changes.htm'
1-navigate to the installation directory
2-move the downloaded files (ERD.uxf, ERD-colored.uxf) to the folder named 'palettes'
3-move Default.java to 'custom_elements' folder on the same directory
you should restart umlet so the changes take place