Check this page and scroll down until you see "Doom 3's MD5 Viewer (*.md5mesh, *.md5anim), (feb. 1, 2006)".
http://tfc.duke.free.fr/
I think this is under the MIT license.
Edit: The Blender MD5 importer/exporter and viewer links can be found on the Doom3 sdk page here (browse down until you see Blender):
http://www.iddevnet.com/doom3/downloads.php