Love to help if you could provide a bit more context.  Do you mean you want a skilled person/company that will facilitate ongoing community engagmenet? 

I recently worked for Communispace (www.communispace.com) in Boston.  That company provides full service community creation, hosting and management - have well over 300 successful commercial communities - global operations. 

If you are looking for an employee or 'contractor' be glad to recommend some folks but need the specifics of the kinds of communities that need to be supported. There is a very big difference in skills needed depending on the audience, goals and community longevity.

Let me know if I can help ( zellmannrohrer_susan@emc.com).

Nattergalen.com offers community management services.

They're the only company that I know of.

Mzinga has a section of their company that does human moderation.  I just happened to be on a webinar this morning where they explained it.