You may ask why you should register your business with social networks. Social Networking can be very profitable for your business. A few ways social networking can help your business is: Providing Marketing on the cheap, Helping you find talent, Finding partners/collaborators, building a business online from start.
A client made a comment about Twitter "I saw people posting from their Twitter accounts bus it was all dum stuff". This client owns a night club that is opening this Friday. I explained to him that he isnt required to follow these people but he wants these people to follow him. He wants them to know what his business is doing, whats coming up at his night club and keep them informed. Youtube and Facebook are also very beneficial. Linkedin is a good one as well. These are the top sites at this time, so where the crowd goes is where your business should go.
Keep your pages active. Keep your topics going. The more active you are the more business and attention you can generate.