Ryan Daigle writes about resource_feeder, a new plugin for Ruby on Rails that makes the generation of RSS and Atom feeds easy. Like so:

def rss
  render_rss_feed_for Post.find(:all, :order => 'created_at DESC', :limit => 10)
end

If you want to get playing straight away:

script/plugin install simply_helpful
script/plugin install resource_feeder