The unofficial Pokémon Go Plus SDK. Implements the protocol for talking to Nintendo's Bluetooth LE wristband.
This project is under active development, and should allow you to create scripted interactions with the wristband in other contexts soon. This will let you use the wristband in other apps than Pokémon Go (e.g. as a general Android notification device) and with other devices (e.g. laptops and smartwatches).
NOTE: This will obviously require you to buy the wristband. The wristband hasn't been released yet, so development has been based on examination of the Pokemon Go client. This is not a replacement for the official Pokémon Go wristband, nor was it ever intended to be. Go buy the thing wherever it's available for preorder; it's $35 and looks like a pokéball.
Lua is a nice language for this in combination with native bindings to the device's Bluetooth LE stack. This will allow cross-platform code reuse on Android, iOS, and any other device with Bluetooth support.
Check the wiki for protocol notes.
If you have a contribution, submit it in a pull request. Please note that all contributions will be licensed under version 2 of the GNU General Public License.