CatBlock is an ad-blocking extension (with an ability to replace ads by pictures) available for Chrome, Firefox and Opera!
CatBlock is open source software licensed under the GNU GPLv3 (http://www.gnu.org/licenses/gpl-3.0.html
). By participating in this project, you give CatBlock the permission to distribute your contributions under that same license. CatBlock's source code is available at https://github.com/CatBlock/catblock