Here are the finished open source projects I started:

Standalone software:

Software with UI:

pwng (password-next-gen) ‒ A configurable password generator and rating tool.

kpt (key-press-timer) ‒ A lightweight utility to time how long a key has been held down.

CLI software:

qc (quick-clipboard) ‒ A lightweight CLI tool to copy file content to your clipboard.

Server software:

mtc (minimal-tor-chat) ‒ A minimalistic web-based chat server. Pre-configured for usage through the Tor network.

Browser extensions and add-ons:

To the Google Chrome browser extensions and Mozilla Firefox add-ons

Libraries:

Java:

nwju (nwawsoft-java-util) ‒ A library containing general purpose data structures and functions.

Haxe:

fen (haxe-fen) ‒ An implementation of the FEN record data structure.

Tutorials:

Building Node.js from source on the original Raspberry Pi (RP1)

And here are some unfinished projects:

Standalone software:

CLI software:

sdp (shutdownplus) ‒ A better way to shut down your PC.
(Status: Needs testing on Linux and Mac. Also needs more documentation, examples and images)