If someone helps you out on this forum, you can add to their reputation as a way of saying thank you in addition to posting a thank you.
I just found this and I would like to show some of the new members guests how to do this.
For example this particular post has helped a lot of people.
Before you do anything, OPT OUT!
In the top right portion of the post is a scale. Clicking on this will give you the option to either approve or disapprove a post.
These forums have helped me out plenty and I wish I had seen this sooner.
Also, a member with more approvals gets more green boxes near his or her name making it easier to distinguish the helpful members and there are many.