Eric Isaacson's A86/A386 and D86/D386 pages preserve a complete commercial x86 assembler and debugger ecosystem built for DOS and early Windows, including downloads, source libraries, Win32 examples, and support for processors from the 8088 through the Pentium III and Athlon.
The QBasic Games Directory survived the disappearance of its original home and returned at Phat Code, preserving a large database from the scene where hobby programmers made complete PC games in Microsoft's beginner language.
Dale Harris's KeyHut POS site preserves a stubbornly practical DOS-era cash-register system built for old PCs, keyboard control, receipt printers, cash drawers, and businesses that do not need a browser to sell something.
Georg Potthast's SIOUX pages preserve packet drivers, NIC detection tools, and practical networking support for DOS-era machines that modern hardware long ago forgot.
MoonRock was Rowan Crowe's 1990s BASIC-like DOS compiler, generating assembler for tiny executables and reaching version 0.50 partly because the author joked that it was half finished.
Russ Nelson's personal homepage sits at the intersection of DOS networking, free software, the Open Source Initiative, and an early religious website he created in 1995.
RetroArchive preserves old software collections, manuals and CD-ROM file libraries, including hundreds of RemoteAccess BBS utilities with original filenames, dates and descriptions from the late 1980s and early 1990s.