Banking laws vary from country to country and even sometimes state to state. Some banks may not be allowed to offer securities and may be only able to offer interest. You might therefore NEED to knock off small niche markets one by one (Facebook model you noted).
The other strategy around Chicken and the Egg problems involves bringing in a third stakeholder, either temporarily or permanently.
I faced the same problem when developing the first web conferencing systems. No one wants to present when there are no audiences, and no audience member want to sign up when there are no presenters of interest. The solution was to pay presenters ourselves to deliver their (formerly primarily live) lectures on our web conferencing system. We found a bunch of popular business speakers like Tom Peters and we hosted their presentations ourselves. People who could not attend their live presentations came to our web conferencing system, not because they were interested in the technology but because they were interested in speakers we set up. Once they came we had evidence of an audience that would be available for future speakers, and this temporary juicing of the market got us started (I guess this is akin to seeding a dating site with fake profiles, or more like paying desirable people to be on your site).
For some businesses you may need a permanent 3rd stakeholder and a different business model. Visitors to a city like San Francisco want to know where are the interesting restaurants, bars, and night clubs to go to. And those venues want visitors to find them, too. But these businesses are often low margin and have very limited advertising budgets. So if you charge the businesses, you don't get many of them signing up. That leaves you with only a small part of the market in your guide, and that's not interesting to visitors who want to see something comprehensive. On the other hand, visitors are used to online information being free, so they don't want to pay either. The solution to this dilemma is to involve a 3rd party advertiser like wine, beer and spirits companies, who want to associate their names with certain venues. Now the listing can be free to venue and visitor and the business model is adding an advertisement into the listing.
I hope one of those techniques are useful to you.