One of the early apps in the iTunes App Store was from UrbanSpoon.com [App Store] which tries to help you answer the question: "Where should I eat?"
If you are fortunate enough to live in one of their supported North American cities or in London, then you can try their app. Almost like a slot machine, it lets you randomly choose between locations, cuisines and price ranges to find a restaurant at random. You are also allowed to "lock" any of these criteria and search on the remainder. For example, if you are specifically looking for an italian restaurant, you can lock in that option, and allow it choose the other criteria randomly. And of course, in iPhone fashion, in order to set the wheels in motion, you just give your iPhone a little shake. (Note that we've heard that the app may crash if you are not amongst the supported cities.)
A YouTube video shows the app in action.