If you use JetPack Stats on your site (formerly released as a stand alone plugin called WordPress.com stats), you may be familiar with the smiley face image that it adds to the bottom of every page on your site.
The smiley face is used to help track stats on your page. I’m not a huge fan of it so I looked into how you can remove it. Thankfully, the recent release of JetPack addressed this issue. If you go to the configuration page for JetPack stats (found at http://www.yoursite.com/wp-admin/admin.php?page=jetpack&configure=stats) you will now see an option to hide the smiley image. You simply need to check this box.
Alternatively, you can add this short line of CSS code to your CSS stylesheet (stylesheet.css):
Another option which many users used before JetPack was updated with a hide option was WordPress.com Stats Smiley Remover. The plugin added the CSS code above to your site header though since the update the easiest solution is just to disable the smiley via the configuration page.