Manji 卍

No idea how many of the links are still active, but Systems of Romance always had cool shit, you can find some good stuff in the affiliated blogs as well

See also: Crispy Nuggets, Mutant Sounds, Ten Thousand Eyes, Kentucky Fried Wave, Fantasmi Macchina

Again, idk how many of the links are active since some of them havent been maintained since like 2k13 but you'll at least be able to find a bunch of varied obscure 70s / 80s post-punk/minimal synth/industrial/new wave/synthpop stuff on those

There's a Russian message board metalarea.org - it's pretty easy to register to, and is constantly updated with new releases (and most of the older releases' dead links get replaced frequently too). This is for the black metal part of your question obviously.  For post-punk I don't know of any other 'one' source except the Stench of Death blog.