This is a fairly unique product – part del.icio.us/popular and part Digg, and based on tags. On the front page of Buzz are very popular recent bookmarked sites. But there is a “Buzz” area for each tag as well. Just type in bluedot.us/buzz/[TAG] to see it. Here’s the TechCrunch page, for example.
Each page is populated based on users bookmarking and tagging a page. If enough people bookmark it, that link goes to the top of the Buzz list for that tag. As soon as another bookmark with that tag makes it over the Buzz threshold, it is added on top of the old no. 1 and pushes everything else down (like Digg). The result is constantly refreshed content relevant to a given tag. Users can subscribe to the RSS feed for that page, too.
Our previous coverage of BlueDot is here.