One of my projects involves moderating and providing content for an online community of tech enthusiasts...and there are a few ways we let people with similar interests know we exist: (1) we put the forum URL in the email sig line; (2) we participate actively in other forums; (3) when we find someone with an expertise we think our members would enjoy, I email them, tell them about our community, and ask whether they`d be interested in being interviewed for the group. That provides more interest for existing members, invites the new person in for a look around, and perhaps if they enjoy the experience they will hang out with us and share what they know.
[On a technical note, do you have your forum software? I was just checking out Community Server a few days ago--it`s free for individual use (but you have to purchase a license if you want to make a business out of it).]
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Katherine Murray | reVisions Plus, Inc. | publishing services for print and online media | www.revisionsplus.com