Quoted from practicalsteve:

How about this, a system where we can "vouch" for someone? Maybe something on a pinsiders profile page but a little indicator in the posts to show how many "vouch points" that person has. Did someone send you a part for free? Sell you a machine at a great price and it was a smooth transaction? Did someone come over and help you troubleshoot something out of the kindness of their heart (or for beer)? Maybe they invited you over to play some pins and you had a great time. Or did someone just go above and beyond in really sticking with you through a tech thread? You can go to that persons page and give a little write up to say that they were a good seller, or buyer, or helpful or whatever. That way when you want to deal with someone you may not know you can see that others have before and had a good experience. I can think of ten people I would do that for on here.