I am aware of few tips but this article summaries few more good tips and techniques that will optimize MySQL Server performance.
Although this article explains how to tune a MySQL database for use with eZ publish system. But most of things mentioned here will apply to other MySQL based software (such as WordPress or phpbb).
This article has suggestions for optimizing for either read or write operations, and also discusses some other optimization techniques such as DNS and filesystem configuration.
Try out these tips and let me know your experience. If you are aware of any other tuning factors please let me know :D