There is a useful extension for Firefox called the Netcraft toolbar. The toolbar is normally positioned below the address bar and shows informations about the URL you are currently browsing like where the site is hosted and since when it exists. It is primarily meant to help detect phishing sites. If you for example reach some site that pretends to be paypal.com and you see that it’s located in China and exists since last Monday you can be pretty sure that it really is only a pretender.
Netcraft has also build in a ranking system for sites. This was an easy addon for them to implement, since each time your browser connects to some web-site the toolbar asks its home at Netcraft for informations about the site. So the ranking system is quite easy. The more people browse to some specific locations the more points those locations gain. Users can also report sites as phishing sites, which is shown in the risk rating portion of the toolbar.
For privacy fanatics like me, installing the Netcraft toolbar is connected with some bad feelings. After all they could create a profile out of your browsing behavior. Naturally they promise they won’t, but then, who knows. Netcraft seems to be a trustworthy company and the danger of them creating a profile for you weights less than the danger to reach a phishing site and actually believe it.
Besides I find it quite interesting to see where the sites I visit are located and to whom they belong. There’s also a handy link to a whois report for the currently viewed site.
The toolbar is highly dependent on the availability of the Netcraft site. If this is not reachable, the toolbar won’t tell you anything and will only create extra network overhead trying to connect to it. I’m using it for a month now and this only happened once at the beginning. They probably underestimated the popularity of the toolbar and used a server which was a bit too weak for its job. But now it works without problems.