GtkSQL is a graphical query tool for PostgreSQL/MySQL.  You can work on
multiple queries simultaneously:

 * send the current query to the database
 * add a new query
 * delete current query
 * rename current query
 * export current query
 * display the table information
 * move to the next or previous query 
 * SQL keyword, table name and field name autocompletion
 * rescan the table database.

WWW: http://membres.lycos.fr/bbrox/GtkSQL/