Promoting your community is part of your job.
Aim to get promotion in trade publications, newspapers, radio, TV. Continually comment on topical stories. Issue statements on behalf of the community on key issues. Get guest posts in blogs. Promote individual members as well as the community in its entirety.
If you work for an organization, your organization should be promoting the community in press releases and through its own contacts. The organization should try to raise the status of being in the community. Refer to the community on the website and in company literature.
Have a place in the community that keeps track of these mentions. Let members know where the community has been mentioned elsewhere.
The goal isn't to attract members (though that will happen), but to make existing members of the community feel an incredible sense of pride. Pride and status lead to increased levels of participation.