Build around your discovery mechanism
blog.cubeofm.com
blog.cubeofm.com
In a pure online play, I think the equivalent of location is channel strategy. Find partners who are a close fit to your offering, and work hard to form a good relationship with them early on. If you can provide a service to their customers that adds value, it's a win for both sides.
Is there really a way of building my business next-door to yours - in the sense that I'll catch customers walking out your door?
The app store analogy holds - the app store can be thought off as a mall where people are walking about. If your store sucks, nobody will come in, but people are seeing it. If there was no such store, your app could potentially be on the web and you only ever have 10 visitors.
On a shopping street, I don't have to be looking for a book store to run into one. I might not buy anything the first time, but now I know it's there. And every time I walk out the clothing store, I'm reminded the book store is next door.
This does not seem to me like a good way to encourage repeat business.
A bar at a bad location is very difficult to keep profitable.