Social Media is used not only to drive sales and revenue but is also used for recruiting staff, disaster recovery in crisis management, launching a product or event and for consumer research. However one of the biggest uses in my mind, is to drive people to your information.
Linkbacks from social sites are really authoritative and send valuable signals to search engines. Social Media matters more that ever when it comes to optimising your information.
Even the White House uses Twitter! When a follower complained that their tweets were boring, they tweeted an apology for the dryness of fiscal policy alongside a link to a Rick Astley video to cheer everyone up!
My last point being, and it was undoubtedly the first reason why social media was used, is that, even as a business, you should have fun 🙂