Here are some of the best free MySQL tools out there. The description is not my review of the product, it is just what the developers say about their tools. If you know some other good ones, you can drop a comment.

From MySQL:
  • MySQL Migration Toolkit: The MySQL Migration Toolkit is a graphical tool provided by MySQL AB for migrating schema and data from various relational database systems to MySQL. MySQL Migration Toolkit is designed to work with MySQL versions 5.0 and higher.

  • MySQL Administrator: MySQL Administrator is a program for performing administrative operations, such as configuring your MySQL server, monitoring its status and performance, starting and stopping it, managing users and connections, performing backups, and a number of other administrative tasks.

  • MySQL Query Browser: The MySQL Query Browser is a graphical tool provided by MySQL AB for creating, executing, and optimizing queries in a graphical environment. Where the MySQL Administrator is designed to administer a MySQL server, the MySQL Query Browser is designed to help you query and analyze data stored within your MySQL database.
From third party:
  • phpMyAdmin: phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the Web. Currently it can create and drop databases, create/drop/alter tables, delete/edit/add fields, execute any SQL statement, manage keys on fields, manage privileges,export data into various formats and is available in 50 languages.

  • Webyog: Just by uploading a single PHP page to your web server, you can use all the cool features of SQLyog. The PHP page exposes the MySQL API as a set of web-services that can be consumed by SQLyog. This is exactly the architecture that MS recommends for all new applications and calls them "smart clients".

  • DBManager Freeware for MySQL: The latest version of DBManager, 3.1.0, brought more power and support for commercial database servers line: Oracle, MSSQL Server/MSDE, ODBC, MSAccess and Sybase. The challenge now is to create a box of tools that will allow you to manage your databases structure and data, create your web pages in languages such as PHP, Perl, ASP, etc. Tools for data warehousing, designing and reporting are also being developed.

  • FreeMascon - MyCon: MyCon is our next generation GUI truly catapulting MySQL 3/4/5 into the same league (and beyond) as MS SQL Server, Oracle, etc concerning client interfaces and functionality. Free/Mascon's features include connections to multiple servers, design, data and blob editing of tables, SQL color coding, security, creating reports and much more. The reports can contain text and charts that are generated from the data in your database.

  • MySQL-Front: MySQL-Front is a graphical front for the MySQL database. Because it is a "real" application, it can offer a more refined user-interface than is possible with systems built on PHP and HTML. Response is immediate, there is no delay of reloading HTML-pages.

  • WinSQL Lite: WinSQL is a "must have" utility for DBAs and programmers who deal with databases. It empowers them to be more productive by providing an intuitive tool that can talk to any database through ODBC.

  • MyDB Studio: MyDB Studio is a complete collection of powerful tools for MySQL Server administration. Thanks to its simple Graphical User Interface (GUI).