Here are many of my favorite links. Do you have any to share? The more the merrier. Knowledge is power!
Electronic/Computer Forums
Savage Chats (https://savagechats.com/index.php) .. of course!
Parallax Forums (https://forums.parallax.com/discussions) All things propeller, and probably the only place.
Sinclair ZX World (https://www.sinclairzxworld.com/) All things Sinclair. Mostly about my first computer the ZX81!
FPGA
Open Cores (https://opencores.org/) A repository of open source FPGA IPs. Sometimes works, sometimes don't
Nand Land (https://savagechats.com/nandland.com) Videos and tutorials on VHDL and Verilog languages. He has good examples, has the FPGA Go Board and a book based on it.
fpga 4 fun (https://www.fpga4fun.com/) Has great examples. Serial ports, oscilloscope, games and more
8 Bit Workshop (https://8bitworkshop.com/) Java Web simulator for FPGA verilog, old 8 bit computer and game consoles. There are links to ebooks that help in using the web simulator.
Project F (https://projectf.io/) Verilog projects and a RISC cpu
FPGAcademy (https://fpgacademy.org/) If you have an Altera/Intel DE board this is a good starting point for setting up projects and the Quartus IDE
Z80
Z80 (http://www.z80.info/) Every Z80 documentation you can find!
Baltazar Studios (https://baltazarstudios.com/) A project site with a Z80/Arduino, Die level reversed engineered Z80 FPGA and a Die level Z80 simulator in java
Ken Stirriff's Blog (https://www.righto.com/) A blog going into the netlist of the Z80 and other CPUs
Simulators
Logisim Evolution (https://github.com/logisim-evolution/logisim-evolution) A java based Logic simulator that can generate VHDL/Verilog files for FPGAs
Digital (https://github.com/hneemann/Digital) Another java based logic simulator similar to Logisim
Simulide (https://simulide.com/p/) a free simulator that does logic, Z80. Arduino, ESP, TTL and other components