Not about Doom, but Quake.

[Espi]

This is a pack of 6 very good maps for Quake 1.

Oh my god! It's full of brown!

This reminds me, didn't someone mention that they're doing some port that could enable Doom levels made with the Quake level format, or something?

Well, it turned out to be a bit about Doom anyway. :)

[Xenoman]

I used to download new maps for Quake1. It was quite fun, but I got tired with castles and fortresses.