How accurate were medieval archers, marksmen, how far could they shoot?

Question

Think of the best, Robin Hood type best. When it came to long shots, medieval snipers you might call them, what's the farthest a bow could shoot and how accurate were they?

Answer 1

A good source for this is:

http://www.usarchery.org/usarchery/html/History.html

Another is:

http://www.centenaryarchers.gil.com.au/history.htm

And another is:

http://library.thinkquest.org/27344/history.htm

Answer 2

According to wikipedia the range of a long bow was 165 to 228 meters (180 to 249 yards). The closer the target,the more accurate it was of coarse. William Tell used a crossbow to shoot the apple on his son's head in the famous legend.