WebPagetest »

An excellent resource for testing and optimizing Web site performance. The information contained in the results is the most thorough of any I've seen.

Web Performant WordPress »

Dave Rupert provides an excellent breakdown of how to speed up your WordPress-powered site. There's no excuse to not spend the time implementing these changes. Even if you're like me, and have already done a lot of the work, I'm willing to bet there's a step or two that will make your site even better. For me, it's the super-duper-easy cut-and-paste improvements to the htacess file to enable gzip and browser caching.