Feedzz it's a semantic feed aggregator. It crawls the most popular feeds (based on different categories), reading the post entries and auto-tagging the entries using OpenCalais. Once the user selects an entry, he/she can find out related entries using the semantic terms as connectors.The information is classified under topics, people and places.

Users can suscribe to existing feeds, submit new ones or upload OPML files. Search and semantic terms can be stored as shortcuts available in the profile page and by webmail.

Users can vote up&down,  share posts (mail and twitter) , and bookmark. posts organizing the post entries in folders.

WordPress Calais Auto Tagger and Archive Tagger - Dan Grossman has developed a very nice WordPress plugin that automatically tags posts as you write them, and another that does the same for your archived posts. While the Calais tagging results are never going to be 100% on target, this is a great tool for improving the searchability of your historical posts in minutes.

The Powerhouse Museum is using Calais to automatically generate tags for items in their extensive collection. For a quick example take a look at this description of a surveying instrument. The tags generated by Calais are allowing curators and others to find connections within their collections that were previously invisible.