The purpose of the website at share.opml.org is to gather a community of RSS subscription lists, in OPML format, and aggregate them in interesting way. An OPML file is essentially a list of the RSS feeds you subscribe to in your preferred RSS reader. Most RSS readers offer a way for you to export your subscription list to an OPML file, which can then be uploaded and shared at the share.opml.org website. You also have the option of sharing your feeds by entering in the URL of your OPML file. Once you're a member and participating by sharing your feeds, you can really take advantage of what the site has to offer. You can view the "Top 100 Feeds" and "Top Podcasts," view the list of the "Most Prolific Subscribers," or query who subscribes to a particular URL, which is a great feature for vanity searches. However, the most useful feature is "Subscriptions Like Mine," which lists all the members of the site who have a feed list similar to your own. This offers you an easy way to discover new feeds may interest you by allowing you to puruse the feed lists of others who have similar tastes in web content.