Flattr4WordPress is a WordPress plugin by axiom7 designed to integrate a Flattr button with your blog posts or pages.
It accomplishes this feat via a simple WordPress shortcode.
At this point, the question becomes “What is Flattr and why would I want a Flattr button integrated with my blog posts or pages?” And the quick answer is: Flattr is a social micropayment platform.
It basically works like this:
You open a Flattr account and you deposit a certain sum of money. Then, you decide how much of that money you will distribute over the course of a month. From there, every time you click on a Flattr button, you will award a portion of your monthly amount to the creator of something you liked.
Plugin homepage: http://axiom7.com/?p=33