I built our coop (BELOW) in two days with some new wood and some old that was laying around. It has a hinged, latched door, roosts and nesting boxes. It is 3 1/2' x 8', and I made it that way so a 4'x 8' sheet of plywood would cover the roof with a little overhang. It has a raised floor, so droppings fall through to be raked out from underneath.

[click on any picture below to see the large version with text]

2 Years Later
We decided to take it down off the piers - the wire floor was difficult for us to walk on, and uncomfortable for the hens. A dirt floor is easy to rake out and they "hang out" inside the coop more often.