Some archive.org chance ISO finds

Stone CD Volume 3 by Stone Design (1996) (https://archive.org/details/StoneDesign_1671541226405)
The Fatted Calf CD-ROM for NeXTSTEP (1995) (https://archive.org/details/TheFattedCalf)
NeXTstep Nebula One and Two App Collections (https://archive.org/details/nebulaapps)
NeXTSTEP Products & Services 1994 Summer (https://archive.org/details/NeXTSTEPProductsServices1994Summer)
 NeXT Computer Software Archive (https://archive.org/details/NeXTArchive)
NOVA - For the NeXT Workstation (https://archive.org/details/NOVAFortheNeXTWorkstation)
NeXT Education Software Sampler 1992 Fall (https://archive.org/details/NeXTEducationSoftwareSampler1992Fall)

Updated the initial post with a few more finds already a while ago.

The following link is not on archive.org and appears to be duplicating the contents of archive.org/details/NeXTArchive (https://archive.org/details/NeXTArchive):
osarchive.org/os/nextopenstep (https://osarchive.org/os/nextopenstep)

Excellent more objective C source code :).

Bad news for @wizard  as that is more entries needed for his database.