Many of us rely on rechargeable AA batteries to power our keyboards, mice, and other peripherals. There are plenty of decent battery chargers available on the market. Aaden is a USB-powered AA battery charger you can connect to your iMac or other computers to charge your depleted batteries.
Aaden does not take a whole lot of space and keeps your batteries charged, so you can keep going with your mouse or keyboard. You can find more information about it here.