If you haven't noticed with the new changes to the forum, it appears we may actually get a working reputation system. We really have never had one before and nobody really reps. The way it works is simple; if someone likes your post, they give you good reputation. I noticed in the old forums nobody really used the reputation, with people like xStarx having only 9,000 posts and only 2 bars of rep.
Here's an example on giving reputation to a post:
To view the reputation you have navigate to your settings and look right under the infractions (if you have any). It should look like this:
(Under that tab you can also see how much you give per rep, and how much you have given)
Remember to stay nice guys! Let's enjoy these new/old? forums!