On my question http://stackoverflow.com/questions/2881589/logging-into-so-with-curl user psmears was extremely helpful to me. Not only did he answer my question but continuously came back with answers to my comments.
I think there should be some way of indicating this on StackOverflow. I was of saying that a user is helpful instead of just a particular answer he gave.
Without getting too specific I imagine a system like On the userpage there is a button says "helpful". Once a user gets X number of clicks on button he gets a badge. This isn't a definite proposal but a prompt for discussion on the topic
edit: to be clear I am aware of the reputation system and its uses. What I'm asking for is some award or indication that a user goes way above the normal answering of a question (correctly) and then leaving or comments a bit. But for a user that actively helps the debugging and clarification of his answer.
IMHO the reputation system is limited to correctly of answers as opposed to the helpfulness of users.