Codecanyon - Viral Lock v1.5 – Like, Google+1 or Tweet to Unlock
Make your site go viral by requiring your users to Facebook Like, Google+1 or Tweet about your site to reveal premium content. Simply wrap the content you want to protect with the [viral-lock] shortcode and the content will be protected until the users shares your page. Viral-Lock is the first of its kind to combine Facebook, Google+ and Twitter to give maximal viral impact. More likes and tweets = More money for you.