TOra is an open-source multi-platform database management GUI that
supports accessing most of the common database platforms in use,
including Oracle, MySQL, and Postgres, as well as limited support
for any target that can be accessed through Qt's ODBC support.

In addition to regular query and data browsing functionality, it
includes several additional tools useful for database administrators
and developers - which aims to help the DBA or developer of database
application. Features PL/SQL debugger, SQL worksheet with syntax
highlighting, DB browser and a comprehensive set of DBA tools.

WWW: http://torasql.com/