Posting on HN is a good start, enough folks potentially interested will see this.
Have you tried asking folks at YC to put the buzz around the office? I have heard a few of the Mixergy interviews where someone (or a group) was going through the YC process, and mid-project either met someone or had an epiphany and changed direction with their project. I only say that to mean that you have a fertile environment of tech folks there that may be wanting to bite into something else or have some ideas to meld into yours to spark something exciting.
Other than that, SF and NYC have huge tech communities, it sounds lame, but maybe put together some form of meetup and see if anyone stands out to you guys? Like a tech in realestate to pitch your existing idea?
Not really sure, but it seems you'll have to come at this from the "organic" angle. Monster.com likely won't get you the folks you want :)
