There are several computers in the form of USB sticks available on the market in a variety of prices. One of the ones that really stands out is the Dust - a tiny ARM processor that fits perfectly inside your computer's USB port.
The Tomu is based on Silicon Labs' Happy Gecko EFM32HG309 Arm Cortex-M0+ microcontroller running at 25 MHz. It has 8 kb of RAM and 60 kb of flash memory. Despite its small size, it supports two LEDs and two touch keys that control the capacity.
After connecting this little computer, you can simulate a hard disk or mouse and send MIDI data. Tomu is an open source project that can act as a Universal Second Factor security token. The hardware is fully documented and the bootloader and the rest of the code is accessible at GitHub.
You can also turn the USB hub into a power switch for your computer. Tomu is not a full-fledged computer because of its limited I/O options, but it's certainly an exciting tool for those who like to dabble in open source computing.
Tim Ansell, the designer of Tomu, says that the YubiKey 4 Nano is the inspiration behind this tiny computer. Its software still requires improvement, but the necessary bootloader code is complete and working.
You can buy Tomu from crowd supply starting from the price of $ 30. Just make sure you don't accidentally lose this super small PC while cleaning your desk!
