I found a web 1.0 website with almost 2700 doujinshi (a lot from the early 00s) of dozens of different IPs that don't seem to be available elsewhere:
http://www.arigatomina.com/downloads/djs/index.html ("soft" yaoi)
http://www.arigatomina.com/downloads/private/djs/index.html ("hard" yaoi)

If anyone wants to save everything instead of browsing page by page, you can go to http://www.arigatomina.com/downloads/ and use a download manager to save the "doujinshi", "raws" and "private" folders.
I'm going to download everything for archival purposes, but I don't know of a good place to upload 24GB worth of content.