Great idea, but like others said make it clear, with one sentence, what your service does (think like you're a restaurant owner who vaguely even knows what an iPhone is - just that a lot of your patrons use them in your restaurant).
Also, using the location-network effect you could also help promote their establishments. Build another app that allows you to search and view your client's mobile-friendly sites and open their location in Google Maps
So its like Urbanspoon, except you can actually see what the hell is on the menu. This helps your product sell more because not only are you making it easier for the restaurant to gain visibility through your promotion and marketing through the app (which is what you could technically charge them for - giving away the site for free), but you are also giving them an established mobile presence as well.
Interesting idea. But that would put us in direct competition with Yelp, Urbanspoon, CitySearch, etc, which already have massive market/mind share. Why would someone care about being listed in our directory?
Additionally, all of those directories already link to the restaurant's website. Our goal is simply to make sure that when the user clicks through to the website, they can actually find what they're looking for.
Edit: That said, explaining that all these existing directories point to your website, and when your customers click through, they want to be able to find your menu (or whatever else wasn't listed in the directory) is certainly valuable.
Also, using the location-network effect you could also help promote their establishments. Build another app that allows you to search and view your client's mobile-friendly sites and open their location in Google Maps
So its like Urbanspoon, except you can actually see what the hell is on the menu. This helps your product sell more because not only are you making it easier for the restaurant to gain visibility through your promotion and marketing through the app (which is what you could technically charge them for - giving away the site for free), but you are also giving them an established mobile presence as well.
One two punch.