Optimizely - A/B testing you'll actually use.
Edit Any Webpage - Edit any site on the fly - bookmarklet
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.
Jam - Portable bluetooth speakers that set you and your jams free. Wireless speakers, great sound quality, and totally portable, need we say more?
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Iteration X - Iteration X allows teams to annotate and edit any live website or web app directly in Chrome.