iw-icon-updater https://github.com/dbbolton
Use this script (as root) to replace the default Iceweasel icons. First look over the 'Options' section at the top of the script file.
The default icon is from: https://wiki.ubuntu.com/IceWeaselIcon?action=AttachFile&do=get&target=IYY_new_tangoish.png
This script is licensed under the GNU General Public License, version 3: http://www.gnu.org/licenses/gpl.html