Just starting out, there are several ways to attract members.
Personally, I handpicked many of my first 100 members (or used the other members to refer folks). So, we built a nice big core of members and built from there.
Always have the members help out. They feel like they have a stake in things and feel a big part of the success of the site. Have them post your RSS feed to their Facebook or Twitterfeed or whatever they have setup. Speaking of Facebook...I get a good amount of traffic and membership from my Facebook page and my Facebook account (with 'notes' comes through based on my Twitter and forum RSS feeds) directly.
But, what it all comes down to is content and/or engaging topics and conversations. You see, you can get the visitors to your site, but it's converting them into members and then the challenge of converting them to paying members after that to help with site costs, etc.
Personally, we have a great community that has really gotten behind our efforts to succeed and it's something that is a point of pride for us at TheWDB.com