Make Google Maps API Get Restaurants In Specified Area

So far I use [URL] to get the longitude and lattitude of some address.

function load()
{
if (GBrowserIsCompatible())
{
map = new GMap2(document.getElementById('"mapHolderID');
map.addControl(new GSmallMapControl());
map.addControl(new GMapTypeControl());
map.setCenter(new GLatLng(lattitude,longitude), 15);
var point=new GLatLng(lattitudelongitude);
map.addOverlay(new GMarker(point);
}
}

So if user enters Downtown it would take the user to downtown. Now what I want is that if user searches for downtown resturants search result should point to downtown as well as list all the resturants in downtown.