Google + 1.
Google has launched the +1 recommendation service which enables anyone with a Google account to, when logged in, to click on the +1 icon that appears next to each search result and build a list of recommendations. These, much like the iconic “Like” status can then be used to determine relevancy by popularity.
+1 buttons can be added to any webpage in a similar way to how Facebook’s “Like” buttons integrate with your content.
It is thought that the +1 button will also begin to influence the way in which Google evaluates the relevancy of its results rankings.
More about implementing the +1 button:
Create your button:
How to add it to your site:
Track your button: