I have been maintaining a list of web sites built on the SharePoint platform since 2006. I find the sites using specially crafted search queries on bing and Goole to find most of the sites. People can also submit a site using this form…
There are nearly 2,200 (279 of them are Education) sites which would make it hard to navigate through them based on normal folksonomy tagging so I used a controlled taxonomy and created a visual pivot of the sites using the Silverlight Pivotviewer control. This lets you easily view sites by country, industry, platform and rating. You can view the pivot here http://j.mp/spssites
Explore the user interface which lets you filter the sites using the refinement panel on the left. The facets can be sorted by quantity or alphabetically and more than one item can be selected from multiple facets.
You can also change from the tile view of sites to a graph view based on any of the facets.
The Silverligt Pivotviewer is a great way of visualising data. To find out more about Pivotviewer, go to http://www.silverlight.net/learn/pivotviewer
I have also created a view of the New Zealand members of parliament (although a bit out of date now) which I use in my education demo on the vale of structured tagging of digital content. http://www.wssdemo.com/livepivot/parliament.htm