I've been using http://www.webpagetest.org which is pretty well known in WPO circles. It's not as "pretty" as your site, but offers more features like recording video, Dynatrace recordings, firstview vs 2ndview, etc.
+1 for http://www.webpagetest.org , it's probably one of the best if not THE best performance testing webapp on the web. I've been using it for a while and it's just amazing. I love your Academy section, as well as the simplicity of the site landingpage.
Webpagetest is useful - it's the best place to get an IE speed report. The reports can take a while to generate, though.
I also like how webpagetest.org includes links to downloadable tcpdump files.