From the Dept. of Losing Big Things in Public Places

This is so cool.

To see where they left their bike, they can look at the map on their smartphone. Pingbell uses Bluetooth Smart to let them know if they’re getting closer or not. They can ping the bell remotely if they still can’t find their bike, and it will ring itself. The sound is rich and full rather than an electronic beep, as it is made of brass so the noise is loud and crisp. Pingbell also functions as a conventional bell if you want to ring it while cycling along, and if you don’t want it to make a noise, it can blink a light at you instead to signal its location.