Nightingale bow. Ebony or Daedric arrows.
From the vantage point of the two pictures bellow, I could snipe bandits off their respective bridges (even as far as the opened eye in the bridge at Valtheim. Actually, the picture of Valtheim is not exactly accurate...I would have been a little further back. Between the big rock you see on the right, and a smaller rock you can not see that would be on the back left.
Valtheim
[img]http://guides.gamepressure.com/theelderscrollsvskyrim/gfx/word/1032902937.jpg[/img]
Robber's
[img]http://images4.wikia.nocookie.net/__cb20111125092650/elderscrolls/images/0/09/Skyrim_robbers_gorge.jpg[/img]
Since patch 1.05, these shots are close to impossible...if not impossible.
With all the crazy stories I hear concerning archery and patch 1.07, you probably look at these shots and say "No f'ing way!".