This beautiful project posted on SN reminded me of the beautiful-in-a-different-way Learning bitcoin from the command line project. It's so cool to see the different resources available to help people get started, aiming at varying degrees of sophistication and assuming varying kinds of background.

What other great technical learning resources are around that people like? I'm particularly interested in ones that have this kind of dive-in energy, not just reference material, although especially beloved reference material is also welcome.