Your members (customers) must be able to control their own community experience, relationships, and involvement. Let them stop anytime, or even become more involved as it is appropriate to them. Help members be a part of something larger while retaining their own individual freedoms.
People join communities to be a part of a larger cause or issue, but they want to retain their own freedom of individuality. This is accomplished by allowing members to adjust and control their experiences. Groups with strict rules are only valued by the smallest group of followers.
Give members the flexibility of being involved in different subgroups, take on certain leadership duties, and establish a voice in the communities direction. This includes letting members influence the results produced by the larger group (whether product produced or services rendered.)
These efforts don't have to be formal, but do encourage a real investment of time and effort-- at the members discretion.