IceCat
"Gnuzilla is the GNU version of the Mozilla suite, and IceCat is the GNU version of the Firefox browser. Its main advantage is an ethical one: it is entirely free software. While the source code from the Mozilla project is free software, the binaries that they release include additional non-free software. Also, they distribute non-free software as plug-ins. (IceCat does keep the triple licensing used by Firefox to facilitate the reuse of code.)"
http://www.gnu.org/software/gnuzilla/
To install IceCat on your computer, try the instructions on the InstallIceCat page.
From the Gnu website: (Previously, this GNU browser project was also named IceWeasel, but that proved confusing.)