Fulltime SW engineer @ SYSGO.
A few years ago I bought a guitar effect, USB-sound-card like device - thinking the support for it will be easy to do in linux... Long story short - it wasn't.
A friend of mine allowed me to use his pebble watch for a few months, to decide whether wearables are for me... A good opportunity to code a few apps :)
Notes for myself to remember...
So you want to build just the cyanogenmod kernel, not the whole 50+GB world...
A home alarm written in python, which uses RFID for authentication, can capture/send pictures via webcam, activate alarm via GPIO.