Internet Speed at a Glance is a lightweight speed test that provides an extremely quick insight into your download speed. This speed test is recommend in the ultimate speed test test.
You can use Traceability at a Glance to check to what extent you can be traced on the internet. It is an easy way to check the correct functioning of your VPN connection.
ZOMDir's Page inspector is an on-page SEO analyser tool. It provides multiple views on a web page for a better understanding of optimization options.
Broken Links at a Glance is the best free online broken link checker there is according to Rusty Result Research. Note that BLaaG for Blogger is a broken links checker optimized for Blogger blogs.
Maintenance Frequency at a Glance helps you assess how often you should check your website for broken links.
Link Quality at a Glance is useful for assessing how convenient it is to have a link placed on another website. It quickly provides insight into the quality of the links on that page, although you have to judge for yourself whether the page is in line with your website.
Website Quality at a Glance quickly provides insight into the quality of one or more websites. This makes it an ideal tool for assessing a website agency's portfolio on technical quality.
There are a few more less important tools which can be found at the page spin-offs.