would it be possible to have a referer field? I.E. could i send someone to shapeways.com/anything/anything.html?ref=mctrivia-346 and on the sales record it would show up any sales as a result of the link. Could be very useful to see how effective advertising is working. My thought is mctrivia would show I refered. 346 is a code specific to an ad I am running. In this way other shops could see if I am refering stuff to them as well as if my ads make sales for me.
For the first part, yes, I think you can do that without much trouble. I have been using ?gid=<whatever info I need here> to more accurately keep track of referers. Would indeed be cool to see this parameter in the sales overview.