The application of social psychology is an important part of creating sucessful social media. Here’s a few good pointers on how to get users to contribute to your site.

• Make it easier to contribute
• Make participation a side effect. For example, Amazon’s “people who bought this book, bought these other books” recommendations are a side effect of people buying books. You don’t have to do anything special to have your book preferences entered into the system
• Edit, don’t create. Let users build their contributions by modifying existing templates rather than creating complete entities from scratch.
• Reward — but don’t over-reward — participants.
• Promote quality contributors