My best salvage was a 5 Star 6 burner gas range from a burn down. The kitchen was spared other than water damage. I haven't cleaned it up yet to see if I can get it to work.
One time on an old house trailer demo that was packed with stuff, I found some old LP's the big ones. Mint condition, still had the inside slip covers. I saw them on the ground as I was running the loader, no telling what else was in there that got put in the can.:beatsme
Not really demo but we re-developed an old CSX storage yard a few years ago. Found some neat old railroad crossing signs - the ones with the big red lights, old glass insulators for telegraph/power lines, buckets of new railroad spikes, some neat old industrial hanging lights, a prefab rail road crossing and a fair amount of old and new rail.
The developer closed on the property and sent us in to start work. Their contract stated that CSX had to remove any items they wanted prior to closing, after closing the developer attained all salvage rights which were given to us. About two days into the clean-up a CSX boom truck shows up to pick up some stuff, needless to say after two supervisors on site and a call to the head real estate guy, they left empty handed.