To introduce community marketing, Wikipedia suggested a following definition: Community marketing is a strategy to engage an audience in an active, non-intrusive prospect and customer conversation. Whereas marketing communication strategies such as advertising, promotion, PR, and sales all focus on attaining customers, Community Marketing focuses on the needs of existing customers.

How do you define Community Marketing?
What is your experience in community marketing? We all know Facebook, but what other communities could be targeted with community marketing tools? Give some good examples?
How to create a community marketing campaign? How to start? What should be considered? What are the main challenges? How to measure the results of a community marketing campaign?
What type of businesses could benefit from community marketing? Is it only a tool for B2C or B2B as well?
In what situations should community marketing be used?