Found this in my logfiles just now . . .
PubSub Concepts provides real-time, content based publish and subscribe systems at internet scale. This site is a Beta version of our home page, which will provide a PubSub interface for weblogs and other information sources.
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PubSub.com reads over 100,000 weblogs in real time, and generates new feeds containing information specific to particular issues.
This chart shows what people are talking about – in all the weblogs and RSS feeds we monitor, how many people are talking about each candidate.
This page has more information: if it was me, I’d put it first, since it has more than one datapoint and a lot of RSS feeds for the infojunkies amongst us.