GUAM is, as the name implies, a GUI frontend to allow easy administration of MySQL users. It is written in Java and uses the Swing toolkit. Since it is a pure Java application, it is completely cross-platform and should work on any platform that has a full Java implementation (and maybe even some of the cut-down implementations). GUAM is released under the GNU General Public License (GPL).
SQLMinus is an SQL Client with many developer-friendly features including :
SQLeonardo is a powerful and easy-to-use tool that lets you query databases. When you work in SQLeonardo, you work in a graphical environment and working with data in this environment means you do not need to understand SQL, the standard programming language for talking to databases.
SQL Admin is a Java client application to connect and send queries to different databases through JDBC. The main idea is to create a multiplatform and multidatabase thin client.
SQL Workbench/J is a DBMS independet frontend for SQL databases. It can be used in batch mode and has strong export and import capabilities. It also offers some extensions to SQL (Variable substitution, BLOB support with local filenames) that try to unify handling SQL databases. It can copy table data directly between two different servers (batch and GUI).