A nice idea, but not one that I agree with.
Like you I have seen some really helpful people who have solved many a problem for others. There are so many reasons why they do it, altruism, kindness, boredom, time on their hands, perhaps.
I have also seen some who are only here for perhaps an hour or two now and again. More than one of the less frequent visitors has brought a great deal to the table, particularly in terms of skill in dealing with a complex issue.
It seems to me the ethos of the place is for all to be helped and for all to have the opportunity to help. I actually think any award however little or even as a token gesture could disappoint many others; in a way to feel unrecognised, it's the way humans react. To that extent it would be counterproductive.
So no, I'm not sending the exocet in your direction, you can coil up the hosepipe, I'm just uneasy about the whole idea.