Fair Share is " a free service that enables you to claim your work, watch how it spreads and learn how it is used across the Web." Their website states:
If it's text and published via RSS, you can claim it: Blog posts, poems, recipes, songs, essays, car reviews, game cheats, celebrity scoops, love letters, you name it.
You plug in your RSS feed (full text feeds are strongly preferred), select a Creative Commons license and give us your email address.
We'll confirm your email address and give you a FairShare feed to add to your RSS feed reader.
Sit back and relax for a few hours while we crank up our engines.
By the time you've finished your nap, the different pages on which your work has been reused will start popping into your FairShare feed.
For each page containing your work, we'll show you how the reuse compares to your license conditions and point you to a handy page where you can see more details.
What does "registered through FairShare" mean?
This is the number of articles or blog posts that have been claimed by our users. FairShare allows you to claim your original work as your own and constantly searches over 35 billion blog and web pages to find where your work has been reused above a certain minimum threshold.