8 free tools for your site, you probably haven't seen before

LoadImpact: http://loadimpact.com, a website load testing service that allows to bring up to 50 simultaneous "users" (robots, of course) to your site for free, while monitoring repsonse time and plotting it. If your site's engine or hosting provider has serious performance flaws - even this free test will show them.

BrowserMob: http://browsermob.com, simple but very beautiful and usable tool that loads target page from 4 different geolocations and shows various metrics per each load, including per-get-query timings.

Alertra: http://alertra.com, an uptime monitoring service that allows a free service called "SpotCheck". It instantly checks your web server (80 port) availability from 11 different geolocations.

site24x7: http://site24x7.com, a similar to Alertra uptime monitoring tool that has 23 different spot to check website from. Very fast and responsive service, I like it.

Host Tracker: http://host-tracker.com/, pure uptime monitoring service which is more than 6 years old. Has an "Instant site availability check" which uses whole their network of 70+ check nodes. A true leader in terms of quantity, however there are some old user and ISP reports about its unreliability.

Enough of those, lets continue with non-typical validators and analytics tools! I do hope I should not post w3c validators here, if you're not aware of them - how do you build anything online?

Webo: http://webo.name/, a real swiss-knife for web front-end optimization. It takes a page you submit and gives it a performance score according to a lot of parameters. Think of it as a YSlow Firefox add-on in the web. I should admit that it not only points to mistakes but also give you reasonable suggestions on fixing them.

CSE HTML Validator: http://online.htmlvalidator.com/ is a replacement to the popular W3 validator, offering very verbose and detailed error descriptions. Also, it provides a lot of suggestions or warnings, which can't be strictly marked as mistakes but are possibly dangerous in some use cases.

Built with: http://builtwith.com/ analyzes target website and gives a profile of software stack it's built with: web server, programming language, statistics system, CMS and so on. Guys behind that service also public trends of those parameters on http://trends.builtwith.com which are pretty interesting. For example, there are still tons of people who use old synchronous Google Analytics JS code.