[Justin]

Just built one today for our new chickens. 4 fenceposts banged in the ground with some corrugated metal roofing that was lying around cut and screwed on as a roof. Going to use some more for a couple of sides but ran out of grinder disks to cut it so, for now, there's some old plywood as a wall.

[heyhay1984]

Ours have cast-off classroom tables so could get same effect with patio furniture, if secured against the wind! One pen also has a bizarre thing I salvaged from PE, looks like you lie back on it and do sit-ups?!

[Kimbo]

we have 2 bad weather shelters. One is the felted-coffee-table  type mentioned above. Its nice and solid and easy to knock up; the downside is that the chooks like to stand on top of it in good weather and they poop all over it.
The second is the Womble-Glastonbury-tent type. This is a bit of a theme here as we also use this type to offer the sheep some extra shade. Very easy and quick to erect and take down and surprisingly effective. the downside to these is that noise of the tarp flapping when its windy....not that our sheep or hens bother about the noise