CauseSense
Firefox plugin to replace Google ads with Social Actions adds.
Firefox add-on project page can be found at:
https://addons.mozilla.org/en-US/firefox/addon/11308
where the plug-in itself can be downloaded.
This is how it would look like if you visit flickr.com:
License
This project is open source. Source code can be found here. It is released under the BSD license.