BuzzMonitor was originally created for the World Bank to help it watch what was being said about it online:
Like many organizations, we started listening to blogs and other forms of social media by subscribing to a blog search engine RSS feed but quickly understood it was not enough. The World Bank is a global institution and we needed to listen in multiple languages, across multiple plaforms. We needed something that would aggregate all this content, help us make sense of it and allow us to collaborate around it. At the time, no solution (either commercial or open source) met those requirements so we decided to build our own.
I checked out the demo page, which shows you the results for a search of feeds containing the keywords, ""HIV AIDS Africa" and "Malaria Africa" from Blogpulse, Technorati, Flickr, Google Blog Search and Google Videos. It was pretty cool, and has an attractive interface. I just wish the demo let you do your own searches to help you figure out how well it works for the issues important to you.