Some social media usage has nothing to do with driving traffic to your own website; instead, it's about being more visible, being seen as an authority in your particular industry, and being helpful to those who don't quite understand your field the way you do. Not only are you doing a great thing by helping those who need help, you're also becoming someone they trust and might bring business to down the line.
When you come from this angle, and you're in an industry that works with the site's main premise, Pinterest is definitely an avenue to consider.
Pinterest is an online pinboard that puts a heavy emphasis on visuals. When a user "pins" something from a website, they're allowed to choose an image from that website to represent the content they're linking to. When you visit the profile of an established Pinterest user, you'll see a number of boards and an array of photos, each linking back to a website.
Take a step back and look at the kind of business you're in. Does it lend itself well to photos? If the answer is yes, ask yourself another question: will people be interested in what you're sharing?
This is the Pinterest account of Myrtle Beach, SC (the city). Myrtle Beach did a great job providing useful content that is also very visual. They have a board called, "Things to Do in Myrtle Beach," a board dedicated to hotels in Myrtle Beach, a board of favorite places/spaces, and a board highlighting the southern food that you're likely to find in Myrtle Beach. In a way, the Pinterest account is recreating the Myrtle Beach experience in photos, and convincing people that they should go without being pushy.
I can see Pinterest being useful for businesses like flower shops, travel agencies, Web design companies, clothing designers, landscaping companies, architects -- really, any business where visuals come into play, or can be utilized in an interesting way. And, as Pinterest continues to grow, I'm sure we'll see more companies jumping on board.