Hi, I've installed and tried WikiLook. I didn't notice it recommending any non-free software. The license is GNU General Public License, version 3.0 as stated on https://addons.mozilla.org/en-US/firefox/addon/7675 . I also got a good (personal) impression of the website http://wikilook.mozdev.org/ due to it's licensing it's style with CC-BY-SA 3.0/ph/ . Seems both free software and free culture friendly.
Cheers -- http://gnuzilla.gnu.org
