Does this image look familiar?  You should, it's all over the web and means the site you are on has a feed. A way to digitally subscribe to the site's content through an aggregator.

Some of you may have heard statistics on how many people are actually using RSS feeds.  I would be very skeptical of any statistics since most users of feeds don't even know they are using them.  Users of MySpace and Facebook, for example, have built-in feeds and is what makes them so addictive.  Firefox interpret feeds automatically and refers to feeds as 'Live Bookmarks.'  RSS is everywhere and will continue to stay.  If you were to ask people if they use Flash or javascript on the Internet most would say no when in fact they might use it everyday. (like on YouTube for example).