Shooting nesting birds is somewhat controversial, I know that BirdForum (UK forum) doesn't even allow shots of nesting birds to be posted due to fears of nest endangerment.
It's also against the law i believe to disturb the nest of a migratory bird so if you do find a nest and decide you need the shot, don't disturb anything, that means moving branches etc. to get a better shot, it could endanger the birds by making them visible to predators.
I don't think you will get too many takers as far as people willing to give out nesting locations honestly.
The best ones are the ones you find yourself anyways.