These Cacti templates extract and graph a huge variety of information about MySQL, giving you very detailed insight into your server's performance over time. The InnoDB graphing is particularly detailed.

The templates and associated scripts have lots of nice features, including code to work around PHP's issues with large numbers on various platforms.

These templates were inspired by the teMySQL Cacti Templates but have many advantages over them. They were developed at The Rimm-Kaufman Group and released as Free Software because of their generosity.

You can see examples of the graphs at http://www.xaprb.com/blog/2008/05/25/screenshots-of-improved-mysql-cacti-templates/

If you need paid support, you can buy it from Percona, where the developer works.