WPSpeedster - Thousands of WordPress themes and plugins tested for speed
Pixpie - Optimize your images and speed up your site on WordPress
Web Load Speed Test - Test your website load speed from 6 locations at once
Website Image Speed Test - Beautiful & easy free analysis of the images on your page
FasterChrome - Navigate the web faster by preloading pages on hovering
OptimizeWP - WordPress speed optimization and maintenance service