Download Squad covered this a while ago…
Serving as a webmaster’s Swiss Army knife, Test Everything! allows you to run a bunch of different tests on your website and domain name, ranging from Alexa traffic details to CSS validation. To use, simply type in your website’s URL, select a category, and check the boxes next to the tests you want to run. When you’ve selected all of your tests, click the “Test website!” button and wait for your test results to be generated. The Test Everything! site will then return a helpful aggregation of links to each of the specific tests you chose.