AmphetaDesk is a free, cross platform, open-sourced, syndicated news aggregator - it obediently sits on your desktop, downloads the latest news that interests you, and displays them in a quick and easy to use (and customizable!) webpage.
Using RhNav - Rhizome Navigation I wrote a data aggregator for Technorati's API. The first result is a video which visualizes blog domains by analysing Technorati's Cosmos (the blogs which link to a particular URL). The video is a screencast of RhNav fetc
APML allows users to share their own personal Attention Profile in much the same way that OPML allows the exchange of reading lists between News Readers.