Check out this lively, modern chicken coop by Nicole Starnes Taylor of MAKE Design Studio.  Taylor designed it for three chickens and their owners in urban Seattle.  With a screen floor and castors, the mobile hen house fertilizes the underlying ground.  Also, the coop has a hinged door for easy access and can be used as a chicken tractor if need be.  Taylor built the 15 square-foot coop with salvaged framing lumber.

[+] More info on this chicken coop by MAKE Design Studio.