Follow changes to any website
These custom feeds are most useful if you want to be alerted whenever a specific page has been updated. For example, if you wanted to follow Google.org’s latest products, just type "http://www.google.org/products.html" into Reader’s "Add a subscription" field. Click "create a feed", and Reader will periodically visit the page and publish any significant changes it finds as items in a custom feed created just for that page.
Source: googlereader.blogspot.com