Website Grader - Grade your website's strengths and weaknesses in seconds.
Optimizely - A/B testing you'll actually use.
PageSpeed Ninja - One-click page speed boost for WordPress
Evergage - Evergage's real time web personalization software can help you boost engagement, increase revenue and drive more conversions. Web personalization software that's easy to use.
WebSite Auditor - The techie's SEO spider: find site issues other tools miss
Google Analytics - Improve your website to increase conversions, improve the user experience, and make more money using Google Analytics. Measure, understand and quantify engagement on your site with customized and in-depth reports.