Social media marketing is all the rage these days. More and more companies and individuals are turning to the social web to promote their products and services and to build and maintain customer relationships. But leveraging platforms of user-generated content for marketing purposes is still a new game with its own evolving rules and best practices. Even the experts are still figuring them out; an awful lot of people are still experimenting. Still, some basic principles and strategies have emerged. Here's what the pioneers in this area have come up with so far.