Hyper Cache is a performant and easy to configure cache system for WordPress.
Housekeep expired transients from your options table
The smallest cache plugin ever released (but still greatly efficient).
Beautifier provides several options to clean up WP's messy (X)HTML source code output, such as code indentation.
This plugin provides the ability to run HTML Tidy through all your posts, pages, and comments, generating a report on just how dirty your code is.
This plugin will automatically clean up your WordPress Dashboard and menus.
A user friendly plugin that helps you send articles to the tidy Network with no effort.