Similar problem: Online ordering for takeout (like opentable for takeout). Getting all the large restaurant chains is one project. Getting the hoards of small, mom & pop, owner-operated restaurants is another project. It's a big challenge. Selling them. Supporting them. In many cases, for example, there's no fancy POS machine. Just a piece of paper. A "dumb" cash register.
There are a dozen websites providing this service already. Since they have to sign up each individual restaurant, they cater to specific cities. My favorite is campusfood.com, which provides online ordering for thousands of restaurants in the cities surrounding over 300 college campuses. They had over 100 restaurants in the Philadelphia area when I lived there. The restaurants don't need any special software or even a computer; orders are placed through the website, optionally paid through the website, and the restaurant gets the order by e-mail or fax.
I was under the impression that this problem had been solved, when I lived in Boston. Foodler and a few others seemed to make this possible with almost every place that had carry out. I put in (roughly) that I want pizza, that delivers near me, at 1am... and it found it.
When I moved to Columbus, Ohio I found that the penetration of these things really hasn't hit as strong nationally. There are some, but not every place does it.
