KSqlAnalyzer is a tool for easy accessing the data of a MS-SQL-Database. The functionality and the look&feel are similar to the program 'SQL-Query-Analyzer' written by Microsoft.
ConceptBase a multi-user deductive object manager mainly intended for conceptual modeling and coordination in design environments. Requieres registration on the page of project.
Aqua Data Studio is a database query and administration tool that allows developers to easily create, edit, and execute SQL scripts, as well as browse and modify database structures. Aqua Data Studio provides an integrated database environment with a single consistent interface to all major relational databases. This allows the database administrator or developer to tackle multiple tasks simultaneously from one application.
Another PostgreSQL Diff Tool (also known as apgdiff) is free PostgreSQL diff tool that is useful for comparison/diffing of database schemas. The tool compares two database dump files and creates output with DDL statements that can be used to update old database schema to new one or to see in what both databases differ.
The best developer's and/or admin's GUI tool for Sqlite3 in the world. No joking here (or just a bit only) - it contains the most complette feature set of all tools available.
MaxDB by MySQL is a re-branded and enhanced version of SAP DB, SAP AG's open source database. MaxDB is a heavy-duty, SAP-certified open source database that offers high availability, scalability and a comprehensive feature set. MaxDB complements the MySQL database server, targetted for large mySAP ERP environments and other applications that require maximum enterprise-level database functionality.