Manji 卍

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.

Haven't used metalarea.org in a long time, but it used to be excellent. If you wanted a demo from1987 that was released in 7 copies, that was the place to find it.

If you don't mind torrents, then metal-tracker.com is really good. Not only black metal, but it's very good for black metal as well as most other metal sub genres. As people who upload have to add their own genre the genre tags might come as cross as a bit messy, but it works. This, metalarea and a few dead black metal blogspots used to be my go-to's for years until I more or less stopped downloading music a few years ago.

thank you,guys...! there's so much good underground stuff on internet

i've been craving more and more