DBDesigner 4 is an interesting (open source and totally FREE) tool for designing your database.
It's a visual database design system that integrates database design, modeling, creation and maintenance into a single, seamless environment.
It combines professional features and a clear and simple user interface to offer the most efficient way to handle your databases.
List of features
- Available on Linux / MS Windows
- User Interfaced based on industry standard layouting software
- Canvas navigation similar to Adobe Illustrator® and Photoshop®
- Palettes (docked / floating) including "Bird Eyes view"
- Available objects include tables, realtions, labels, regions, images
- Extensive Drag'n'drop support
- Extensive Popup-Menu support
- Advanced Editors
- UNLIMITED Undo-/Redo- functions
- Copy-/Cut-/Paste clipboard functions (XML, DDL)
- Align functions
- Design Mode / Query Mode
- Reverse engineering MySQL, Oracle, MSSQL and any ODBC databases
- Userdefined schema-generation
- Model-To-Database syncronisation
- Index support
- Automatic foreign key placement
- Weak entity support
- Standard Inserts storing and sync
- Full documentation capabilities
- Advanced model printing
- Output as image
- All MySQL datatypes with all options
- User defined datatypes
- Database storage, ability to save model within database
- Network-/Multiuser access through database storage
- Version control*
- SQL Query Builder
- SQL Command History
- SQL Command storage within model
- Plugin interface
* Version control only available when using database storage
Wonderful tool! 
