It requires a great deal of work to maintain a community, and the majority of that work resides in moderation. You must be able to censor vulgar posts, to remove unwanted users, to stem the tide of self-promotion, and to move incorrectly placed topics. The larger your forum gets, the more moderating you have to do. Most large forums recruit moderators from the userbase to help with the moderating tasks. Being asked to be a moderator can be a way to reward active and loyal users, additionally you should only ask people who you trust because your moderators will be given a great deal of power by necessity.
How strictly you moderate your forum will likely depend on the type of forum that it is. You can basically divide forums into two categories: work related and non-work related. Work related forums need to be moderated more strictly because maintaining a professional atmosphere is important in getting advertisers. Advertisers want to advertise to businessmen, not to miscreants. By keeping your forum focused on professional activities you make advertising more attractive to companies related to your topic.
Non-work related forums can be moderated much more loosely. Forums that revolve around games, music, or movies do not need to convey a professional image, simply because the forum members do not share a common profession or industry.
One way to think of things is that behavior that would not be appropriate at work is also not appropriate at a professional forum.
In addition to providing the obvious benefits of increased page views communities also provide other indirect benefits.
One is an increase in use loyalty, this manifests itself is a variety of ways. For one users will be visiting your site more often, for two users will be recommending your site to others, for three loyal users and site administrators will get to know each other resulting in a mutually beneficial relationship of idea exchanges.
A community can also be a valuable source of content. In addition to the content provided by user posts, monitoring said posts may clue you in on who might be able to write an article for you. Additionally you could turn particularly useful posts into articles without much work. Loyal users are often willing to contribute content without any compensation other than recognition.
Your community can also keep you abreast of developments in your industry. You cannot read every news story or magazine article related to your Industry, but if your forum is big enough chances are someone has read it - and they might post about it. In a way a forum can become the private news service for you and your visitors.
A final benefit forums provide is the ability to test out new ideas and conduct polls. If you want to know what your visitors want, asking loyal forum users is an easy way to find out. You can only preview new services for forum members to gauge public reaction. All in all your loyal forum members can be an asset in figuring out how you should shape your site.