The Stack Exchange network of websites has a good way of dealing with reputation. You get points for answering questions, accepting answers etc. The more points you have, the more rights you are allowed on the site. Although Stack Overflow etc aren't exactly forums....
It's a brilliant system in my view, though it is geared towards asking single questions and getting the best answer rather than building a community. I can be damn sure though if I post a good question on SO I'll have a good few answers in the space of half an hour, and generally speaking they'll be constantly edited to make them better. Then again, SO does have a much, much bigger user base than here (and the vast majority of other forums!)
I agree with the OP though, handing out rep to new users that have helped should probably happen more (and I'm not excluding myself from this either!) It'd be good to see some new "up and coming stars" around here