The Nanite 85, a nano-sized ATtiny85 devboard with USB Bootloader - most likely the smallest one ever.
The repository holds the Eagle circuit, PCB design data and a software example to handle the soft reset-button.
See Blog post for more information.
I teamed up with Watterott on making the Nanite 85 available for everyone. You can get one here. Note that changes had to be made for manufacturability.