O.k., so I just got a book about marketing on Pinterest, and if you aren't on this, you need to be! Now, this is a work in progress, but here is one of my boards: http://pinterest.com/fairygirl28/bridesmaids/
All you have to do is get an account, download the "pin-it" button to your favorites, and open up a card you want feature. Click "pin it" and stick it on your board! No matter how many times it is re-pinned it will send you straight back to GCU for that person to re-pin your card. Here's the link to the e-book on Amazon http://www.amazon.com/Branding-Business-Creating-Pinterest-ebook/dp/B00792SJ0U/r ef=sr_1_4?ie=UTF8&qid=1342540808&sr=8-4&keywords=pinterest
(I'm not getting any money to tell you about it, I just think it's awesome!)  Please note: if you are extremely familiar with Pinterest already the book might not be very helpful, it is awesome for beginners! If you are already marketing on Pinterest, feel free to share your ideas! Remember, any way we can generate sales on this site is a help to us all!

I think it would be hard to tell if that is where our sales come from, however, you can tell how many times an item has been repinned. And if you use the "pin it" button it will send someone directly to the link to purchase the card. I suppose you could measure it by card clicks to a degree.

We post Valxart's zazzle products on Pinterest at http://pinterest.com/valxart and get lots of repins and likes but no trackable sales yet. I had trouble previously getting correct icon but pinit buttons work great

you can get a pinit button at http://pinterest.com/about/goodies/
 
Once pinned with the pin it button, you can add your zazzle or your GCU artist code to the link .