Maatkit is a group of perl scripts that provide advanced methods of administration for Mysql.

Here are a few of the more useful things that Maatkit allows you do to:

1. Monitor MySQL replication delay
2. Make a MySQL slave server lag behind its master.
3. Ensuring slaves have the same data as masters
4. Find duplicate indexes and foreign keys on MySQL tables.
5. Execute SQL statements and print statistics.
6. Execute queries on multiple servers and check for differences.

Here is the link to the Maatkit website which provides more details on each of the scripts.  I will be providing some real world examples of Maatkit usage in another post.