"You always need a bit of rope" Sam Gamgee,Lord of the Rings

The thread on ice axes for general walking got me to pondering what items of climbing gear would indeed be useful for "general walking."
Aside from the carabiner used for a keyring, I would say that a "bit of rope," used properly to get over the bumpy parts, would be the most most generally useful.

"used properly" is a key phrase. Used improperly, a rope can mess you up thoroughly, but that is true of many gadgets...

Some of this comes from the time when I worked at Canyon de Chelly, where I soon learned to EDC at least 60 feet of 9mm kernmantle, whether on foot or in a vehicle. We are talking about real climbing rope, not stuff from the hardware store. Never hang from rope from a hardware store.