I've definitely had luck with pinterest! I have two items in particular that seem to not only get repinned quite often, but are sold about as often as they are pinned. I never expected those two to be my best-selling items, but I guess that's the way it works sometimes.
I do have just about as much luck with Facebook as I do Pinterest, but I have over 3000 fans on Facebook and include share-able quotes on a lot of my images, so they are shared, with the shortened Etsy link from Bit.ly so I can track what goes where. Seemed to work out great for such little effort.