One of the best possible books you can read for online communities is Influence: The Psychology of Persuasion by Robert Cialdini. Robert explains the basic psychology behind many of our actions.
Importantly, you can use these as psychology hacks for your community efforts.
- Do something for them first. If you want someone in your community, or your community as a whole, to do something for you - try doing something for him/them first. The results are staggering. The more you do for others, the more others will do for you. If you want someone to join your community, join their community first. IF you want your entire community to do something for you, then make sure you're doing something for them first.
- Ask for a commitment. When people join your community, have a brief chat with them. ask them what they will contribute, what they want from the community and hold them to their goals. Or better, set them as profile goals. People stick rigidly to their publicly stated goals. Ask your community to state if they want a forum, then add one.
- Spotlight the positive examples. When confused, we look towards what others are doing. When some members of your community are doing something you like, publicise it to the rest. Shine the spotlight on the members taking actions that develop the community.
Develop authority figures. People obey authority. Christ, policemen, teachers and doctors fall into this category. Authority isn't power. You don't need to be the authority in your community. You need to identify and support others to become authority figures. Then when you need to send a message to your community, invite the authority figures to do
Use liking to grow your community. Liking is the key to viral marketing. People are more influenced by people they like. This is why it's far more effective to encourage existing members to invite more members, than hunting for new members yourself.
Reduce quantity to stimulate demand. Give people a limited time to join your community, limit the number of volunteer positions, only give a member 1 invite (which expires) each month.
There is more to this, so buy the book.