The latest version of the most used web browsers like Mozila FireFox 1.5, Microsoft Internet Explorer 7 or Safari have a nice feature to discover RSS feeds. This feature is implemented as a little icon on the address bar that indicates if the visited website offers a RSS feed. Allowing you to read and bookmark the feed with one click.
This is also available in older browsers thru a plugin like Active Web Reader or NewzCrawler.
So if you are a webmaster and have a RSS feed in your site and you want to enable the RSS discovery icon in most browsers you have to add this tag inside your html <head>:
<link rel="alternate" type="application/rss+xml" title="Juan Pablo Rizzo's Blog" href="http://blogs.tryandcatch.net/jprizzo/rss.aspx" />
Of course you have to change the title and href values to the corresponding website.
You are allowed to have as many link tags as RSS feeds you have.