Some small pieces of code that I use on my daily basis

returns current power draw in Watts. Auto detects multiple batteries. Indicates charging with "↑", otherwise discharging.
- Watts designates idle state: battery is essentially internally disconnected.
Use --plain switch to make the output simple (for non-kArgos users)

Raspberry π ACPI necessity. Adds this one crucial button. No more SSHing a RPi only to shut it down even though you have physical access to it. It can trigger different actions based on the duration of the press.
It uses BCM numbering (wiringPi -g).
My default actions are shutdown and reboot.
My preffered GPIO is some on CSI connector (I²C line?).
My preffered button is iPhone 3GS home button glued to the USB casing.
<to be done>

Shairport-sync is a great project turning any linux computer into a AirPlay receiver. I happened to install it so many times (trying to make it work), that this might be useful https://github.com/mikebrady/shairport-sync