When you press the button on an Amazon Dash, we (used to) increment the Salt Mines gyro counter. These days it just restarts the dashboard GUI when it gets wedged on the Raspberry Pi.
It works by listening for DHCP DISCOVER packets matching the Dash button's MAC address.
Inspired by this article by Ted Benson.
This runs on the Raspberry Pi in the office. I develop it on my Mac and cross compile it for linux/arm. If you're on a Mac, you can install Go with:
$ brew install go
Once that's done:
$ GOOS=linux GOARCH=arm go build
Then scp the gyro-button binary to pi@dash1.local and copy it to /usr/local/bin:
$ sudo mv ./gyro-button /usr/local/bin/gyro
And start the service
$ sudo systemctl restart gyro