What other devices can we use our Li-Ion cells in?

Most of our flashlights use li-ion cells… and we have plenty… but what else can we power with them?

Electronic cigarettes, lasers, chargers that can use the cells to power a usb port… Power banks?

What else?
Please provide links to actual products when possible.
Thanks.

Soldering irons: http://www.instructables.com/id/Solderdoodle-Pro-20-USB-Rechargeable-Soldering-Iro/?ALLSTEPS

http://www.chargedaily.com/18650-devices/

There are 18650 small portable fans like this one:

https://www.amazon.com/efluky-Speeds-Portable-Light-Table/dp/B00XZX7L3I