IgniteOS - "Ignite Os is a simple linux OS focused on productivity and git tools, optimized with all drivers to run on Chromebooks, Netbooks and micro boards." Under active development.
Cloudron - "Cloudron is a platform that makes it easy to install, manage and secure web apps on your server. You can install Cloudron on your server (from say AWS, Digital Ocean etc), give it a domain name and start installing apps." Free up to 2 apps, then $30/month.
JollysFastVNC - Secure VNC/ARD client (which lets me have both Linux & Mac boxes open as remote desktops at the same time).
Rete.js - "Rete is a modular framework for visual programming. Rete allows you to create node-based editor directly in the browser. You can define nodes and workers that allow users to create instructions for processing data in your editor without a single line of code."
Nota - Terminal-based calculator that handles things like radicals and Greek letters and trig functions.