Pinterest at the moment is best for online shopping promotion. 87% of the user profile of Pinterest currently is female (just an interesting fact I would like to mention). If you have hubs with big and beautiful pictures, they will attract attention and drive traffic.
I was invited to join Clipboard and created a profile there as well. It is very similar to Pinterest and it will be interesting to see how it will grow in future.
I like Pinterest and Clipboard more than social book marking sites.