Keep at it. Forums are a big part of it. Nothing can take the place of meeting people though. Have you been to any of the conventions? Ad:tech or Affiliate Summit? They are very much worth your time to attend. We've also done ads on Yahoo and Google in the past. Building your site's ranking up is imprtant as well.

Have you considered joing a network? I can point you to a couple of contacts around the biz if you'd like. Let me know.