Well in my short time on here, I have seen signs used as:
roofing material,
concrete forms,
table top
well cover
septic tank cover
fence material
thermal shield for a furnace (that beautiful Husky sign!!)
shute for grain
and I believe one was used for a chick heater reflector.

So nothing will surprise me anymore but it is still great to see stories like this. Thanks for sharing with us on OG.