GNU License Logos
If you are releasing work under the GFDL, or version 3 of the GNU GPL, LGPL, or AGPL, feel free to use these buttons on your site or in your application to advertise the license. These logos are immediately recognizable, and will assure your users that their freedom is being protected.
Alternative logos by Christian Cadena
Christian's logos are available under the CC-BY 3.0 license.