The Site Check .com does just what the name says. You can check any website for Page Rank™ (PR), Whois details (who owns/registered it, nameservers etc.) and the loading speed as well. Also listed in the results is the Alexa Traffic Rank plus major search engine backlinks, indexing and directory listings info too. This information can be useful if you want to monitor any changes you've made or if you want to buy or sell a website. There are many factors that determine these results and it is all checked automatically for you. Note: it can take up to a minute or so for the results to appear so please be patient, a lot of checks have to be made.
You can check as many sites as you like (one at a time) as often as you like, and all for free.