DbWrench is a multi vendor, cross platform database design and round-trip engineering software. DbWrench's features include: a graphic entity relation diagram (ERD) designer, ability to forward and reverse engineer databases, a syntax highlighting SQL query editor, and support for many of today's most popular databases. DbWrench is written in pure java allowing it run on numerous operating systems.

Here are some key features of "DbWrench":

Generate HTML documentation of database designs
Export ERDs to PNG and JPEG formats
Color coding of database tables and foreign keys
Table templates make adding common columns easy
Add foriegn keys with a single click
SQL is customized for each specific DBMS
Synchronization scripts generated based on current server database schema
Generates a log of forward engineering results and errors
Select portions of SQL scripts to execute
Reverse engineer existing databases
Translate database schema from one DBMS to another
Full round-trip engineering including generating update scripts
Currently supports MySQL, PostgreSQL, Microsoft SQL Server and Access
Multiple operating system support
Syntax highlighting editor
Create abbreviations for common commands and entity names
Execute multiple queries simultaneously
Display query results in tables or as text
Sort result sets by clicking on table headers
Translate common proprietary DBMS commands to another DBMS
Support for most PSQL commands

Homepage: http://www.dbwrench.com/