Joe

bash
AutoKey
GNU Tools (awk, sed, ...)
Technical editing (English)
Tool building
KDE desktop configuration

Learning about cryptocurrencies - as a user

AutoKey user support
https://github.com/autokey/autokey

Duplex - Duplex (two-sided) printing emulation for printers which do not have hardware support for this (Linux).
http://sourceforge.net/projects/duplexpr/