I'm on another forum, outside of woodworking, that has something like this. You click on a little icon and it adds to the other guys "reputation". Then guys go around trying to collect "reps". Every time someone helps someone they expect to be rewarded with reps. Every time a newbie comes along, the whole reps scheme has to be explained. When I ask a question, I have to give reps to anyone that answers, no matter how stupid the answer
. In all honesty, I'd rather thank everyone and go over what I actually did regarding my question than have to go post-by-post and "rep-up" everyone. The admins also had to implement some sort of scheme to prevent one person from repping-up another too often. You have to spread your reps to others before you can give the same guy reps again, so then you have to post that you would give reps, but you're locked out.
That all said, it does encourage participation in threads that are often considered "ugh, not another newbie asking about that" type of threads. But, I think it also adds noise to a significant percentage of threads.