I believe word-of-mouth is a powerful tool (word-of-email I suppose) and obviously cost effective. I was recommended here by my JV partner Chris, and I have already recommended the site to my JV partners. Why wouldn't I...the site is ingenious!! (congrats Mike)
I did a quick alexa search for JVNotifyPro.com and noticed traffic to the site has declined by 16% in the last 3 months. However, from reading these posts traffic doesn't seem to be the main issue - it's getting people to post.
Maybe if we could offer an incentive to get people posting? However, I suppose gaining new JV partners is an incentive in it's own right...so I guess what I should be asking...what could we do to help?