One of the keys to any decent social software project is making it useful enough to the individual that they generate the data that makes the network useful. FeedTagger seems poised to do this.
The idea is simple. FeedTagger is a web based aggregator that allows you to browse not only by feeds and folders like existing aggregators but also by tags, tags you assign on a per feed, or per item basis.
Right now the emergent social knowledge community is just a flicker of potential, but in the mean time its a very interesting re-thinking of the aggregator.
update: this bug