We've just started a "Pop Culture" discussion forum (link in sig). It's pretty general in subject matter.
We're investing quite a bit in traffic and design (design contest posted here, please enter!).
We're also holding contests to entice new users to join and participate.
We've seeded the site with RSS feed posts, hoping to attract folks with some topics to talk about.
What else can we do to attract users? How do I get the site in front of folks likely to register?
This is our first try at a discussion forum site and we're willing to learn from the experts here!