For example it would show you all restaurants in, say, 5 mile vicinity from whenever you are. But most likely you will not be interested in the restaurants which are located behind you. You would rather not spend time turning around and going back. So in simple case your search area should be shaped not like a circle with radius of 5 miles with you in the center, but rather as a rectangle extending along your route with some reasonable distance on both sides. This would make your search aware of your route.
In more general case I wish my navigation system to be clever enough to search in a “detour” mode, assuming than whatever I am searching for is just a stop on my path and I would want to continue to my ultimate destination afterwards. In this case it could use different distance metric to filter and order search results. Now it orders them just by distance from my location. What I really care is how much detour to given place will extend my route. For example, let us call my current position A and my final destination Z. There are two potential restaurants, say, B and C which fit my search criteria (Indian food most likely, in my case). Instead of using distance AB and AC it should build a route A-B-Z and A-C-Z and compare overall time from A to Z over each of these routes. It would be especially nice if it would use traffic information, if available.