2011, Vladimir nettsundere Kiselev
Released under GNU General Public License v2 (GPL) http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
nettsundere/redmine_karma_police
(Pretty old) Karma (rating) for redmine users (plugin). You can set permissions to vote and to view in user's settings page (admin can do this only)
Ruby