SimpleFeed - feed parsing the easy way :-)
Create an aggregation site which aggregates RSS feeds and outputs them in river of news style pages with the most recent news items first.
a console RSS aggregator, written in Ruby
Google's online feed reader now allows you to track changes on any page - even those that don't feature an RSS feed. Google will create its own custom feeds for these sites and update the feed whenever it notices a change. Google Reader will display a short snippet of the page changes in the RSS feed.