Days ago, you would pick a picture from a magazine and rip it out and stick it to your wall. That is essentially what Pinterest has taken up online. Each person has an electronic 'board' which they can pin things to. Boards are mostly images linked back to their sources and to others to like it, to allow friends to login and comment.
Businesses can take it further. A virtual catalog of the products that your business sells, displayed so people can take one and run with it.