Hand-powered air compressor
The day before we left for the exsursion we discovered our car had a flat tire. Could we get it to the shop under its own power, if we re-inflated it? Or would the leak be too much and it doesn't last the journey? Fortunately the leak was small enough, it made it across town just fine. Good thing we had this air compressor in our garage to re-inflate the tire. It only took about 100x as long to inflate the car tire as a road bike tire.