Great information Titan.
Id also like to add a great RSS script thats VERY easy to use and its a very simple include to add the parser to any page you want to display rss feeds on.
Its called magpierss and is a open source script.
http://magpierss.sourceforge.net/
It parses RSS 1.0 RSS 2.0 and ATOM Very simple to deal with and works very well.
See an example of it on
www.newsinsider.org
It creates the feeds on the right hand table displaying the top stories from cnn (reuters? whatever), and the include is just a few lines long.
I had woj do some fab tweaks on some of it as well, so its easily customizable by someone in the know.