This is one of the fastest growing professions in the internet industry. An online community manager, like a 'real world' manager, may have a number of roles, but overall the job involves helping the online community to run smoothly, helping all those involved to work with together and promoting the company or organization's goals, vision or values.

In a for-profit online community the online manager may be involved with promoting certain brands, products, lifestyles and so on. in a not-for-profit organization such as an academic or research forum, the manager may be responsible for upholding standards and ensuring the best cooperation, sharing of ideas etc.

Anyone who has a blog and invites comments is an online community manager, even on the simplest level. Managing the posts, dealing with questions that arise, maybe stepping in if there are disputes, creating and upholding guidelines for using the forum, getting technical problems solved - these are all part of the role.

This job description should give you more of an idea about this.