You can do all kinds of things with an Apple Watch. There are already plenty of silly apps available for it. Wouldn’t it be nice if you could use your watch to get things done around your home? The Apple Watch Door Unlocker happens to be a fun project that shows you how to open doors at home or work with a tap on your wrist.
You are going to need an RFduino module, an iPhone and Apple Watch, and an electronic door strike to get started. The source code for this project is available on GitHub. More information about the project is available here.