clicking thanks will add one point to that person
when you click thanks, you need to refresh to see the the message that you have thanked them.
the chicklets are based on points system. for every 100 points you get, you add a dark green chicklet. for every 200 points after 500, you get a light green chicklet.
clicking on the scale thing on the upper right portion of every post will add a "rep" - the number of points of which is dependent on the rep of the person giving the rep.
edit, no. 5 beat me to it.