As an example I did a quick search for “Diabetes” – a massive marketplace and loads of products… or there should be.
An RSS feed which you subscribe to is your personal subscription to a service, just like email.
A private subscription service for text, audio and video content, even involving a paid subscription fee has been possible for more than a year, based upon RSS.
I was just browsing Technorati.
It would only take 67 favorites to get in their top 100 favorites
Top 50 – currently only 115 favorites
327 Favorites to get in their Top 10 !