I use Google reader to track changes in web sites for which I have an interest. Google reader uses RSS - it provides a list of the sites that have new items, so that you dont have to continually check them for new material. If you have a large number of "favourite" web pages, it can save a huge amount of time. You just log into Google reader, and click on the new articles.
It always irked me that the Air-Stream/tracker page didnt have an RSS feed - so I had to check it manually!

