Syndication and Feeds

FeedTree
Collaborative RSS and Atom delivery using using peer-to-peer multicast. Includes information for readers and publishers.
http://www.feedtree.net/

FriendFeed
Allows you to build a customised feed of made up of content your friends on other collaborative sites have shared, including news articles, photos, videos and comments left.
http://friendfeed.com/

GeoRSS
Provides details of how to add geographic data to RSS and Atom feeds using Geography Markup Language (GML) or the simplified GeoRSS standards.
http://georss.org/

What is RSS/XML/Atom/Syndication?
Introduction to syndication from the weblog of Dave Shea.
http://www.mezzoblue.com/archives/2004/05/19/what_is_rssx/

Wikipedia: Web Feed
Encyclopedia article on the topic, including benfits, technical definition, and basic information on how to read feeds.
http://en.wikipedia.org/wiki/Web_feed

Yahoo Pipes
An interactive feed aggregator and manipulator. List of 'hot pipes' to subscribe to, and ability to create your own (yahoo account required).
http://pipes.yahoo.com/

What is this RSS, XML, RDF, and Atom Business?
Article from the eNewsletter Journal, including consideration of the likely impact on the online newsletter business. <small>(August 9, 2006)</small>
http://www.internetviz-newsletters.com/internetviz/e_article000224613.cfm