I am at the same stage at the same sector, though I am in Brazil. My startup is a loyalty program for bars and restaurantes based on Facebook's checkin.
What I am doing for the last month is a kind of "door-to-door sales". At least my product may benefit if my clients are geographically concentrated. So I selected two neighborhoods with a lot of restaurants, then went door to door asking for the owner just after lunch.
Local biz owners are usually at the business, so it is not hard to be introduced to them by whatever employee you aproach first.
This won't give you scale, but I would strongly recommend you to follow PG's advice: http://paulgraham.com/ds.html
Doing this not scalable door-to-door aproach you will learn a lot (I did), it is a great form of customer discovery. And if you are able to acquire a few customers on the same neighborhood, quoting the same PG's essay:
"Sometimes the right unscalable trick is to focus on a deliberately narrow market. It's like keeping a fire contained at first to get it really hot before adding more logs."
I actually could get in my hand a XLS with thousands of restaurant's emails, but decided not to use until I get closer to product/market fit through this door-to-door tactic.