I would like to introduce a 'karma reward system' in order to a) motivate people to contribute and b) to crowdsource ratings both for people as well as content.
I am leaning to something that is in-between what http//thesixtyone.com offers and HN's or stackoverflow's floating method of ratings.
I am looking for suggestions, formulae and good links to resources, books etc as well as other sites than the above three that you favour.