The following fall under the GNU General Public License v2. Read 
GPLv2.TXT for details.

+------------------+
| PROGRAMS\DEVELOP |
+------------------+

FreeBASIC
PROGRAMS\DEVELOP\FBC
The FreeBASIC compiler (fbc) is licensed under the GNU GPLv2
or later.     --------

FlDevDOS
PROGRAMS\DEVELOP\FLDEVDOS

DeuTex
PROGRAMS\DEVELOP\IWAD\deutex

DMapEdit
PROGRAMS\DEVELOP\IWAD\dmaped43
However, there are a few restrictions in regards to selling copies and 
authorship. See the DOCS\DMAPEDIT.DOC file for details.

MegaZeux
PROGRAMS\DEVELOP\mzx270

OHRRPGCE
PROGRAMS\DEVELOP\OHRRPGCE

+----------------+
| PROGRAMS\GAMES |
+----------------+

BOOM (DOOM WAD player)
PROGRAMS\GAMES\boom202

DOSVICE
PROGRAMS\GAMES\EMULATOR\dosvice
However, according the the README:

    The ROM files in the `C128', `C64', `CBM-II', `DRIVES', 
    `PET', `PLUS4' `PRINTER' and `VIC20' directories are 
    Copyright C by Commodore Business Machines.

    The ROM files in the `C64DTV` directory are Copyright C
    by Commodore Business Machines, as well as Mammoth Toys,
    a division of nsi ltd., Digital Concepts DC studios  
    inc., Ironstone Partners ltd., and Toy:Lobster company 
    ltd.

ElectrEm
PROGRAMS\GAMES\EMULATOR\ElectrEm
However, according to roms\cpyright.txt:

    The Electron system ROMs are copyright Pace Micro 
    Technology PLC, http://www.pace.co.uk. They do not fall 
    under the GPL.
    
Frotz
PROGRAMS\GAMES\EMULATOR\Frotz240
** INFOCOM/INFORM COLOUR UTILITIES by Graeme Cree were not originally
   included with the DJGPPFrotz240Src.zip package and contain no
   license information but are just batch files, so it should be safe to
   assume at they are at least "freeware."

PCAE
PROGRAMS\GAMES\EMULATOR\PCAE

ZSNES
PROGRAMS\GAMES\EMULATOR\ZSNES

+-------------------+
| PROGRAMS\GRAPHICS |
+-------------------+

GrafX2
PROGRAMS\GRAPHICS\GFX2B965
**However, technically this compiled version is freeware but the project 
  itself seems to have later changed its mind to being licensed as 
  GPLv2. There are also a couple of websites for GrafX2, none of which
  seem to have pre-built binaries for DOS. Luckily, I have a copy from
  a while back.

+----------------+
| PROGRAMS\MEDIA |
+----------------+

MPlayer
PRORGAMS\MEDIA\MPLAYER

TheOuterLinux's favorite LMMS and ZynAddSubFX instruments
PROGRAMS\MEDIA\SCLUB\TOLEXTRA

+------------------+
| PROGRAMS\NETWORK |
+------------------+

LINKS
PROGRAMS\NETWORK\LINKS

...If you go to the website, and yes it still exists, it has a link to 
GNU Nano website (https://www.nano-editor.org/). All of the evidence 
suggests that this version of Nano is GPLv2.

MicroWeb
PROGRAMS\NETWORK\MICROWEB

+-----------------+
| PROGRAMS\OFFICE |
+-----------------+

wvWare
PROGRAMS\OFFICE\FLW12con\wv103DOS

+-----------------+
| PROGRAMS\SYSTEM |
+-----------------+

catdoc, catppt, xls2csv
PROGRAMS\SYSTEM\BIN\CATDOC
PROGRAMS\SYSTEM\BIN\charsets <-- Needed for catdoc to work
PROGRAMS\SYSTEM\BIN\catdoc.exe
PROGRAMS\SYSTEM\BIN\xls2csv.exe
Site download: http://www.wagner.pp.ru/~vitus/software/catdoc/

FoxCalc
PROGRAMS\SYSTEM\BIN\FOXCALC.EXE

FreeDOS Edit
PROGRAMS\SYSTEM\BIN\FEDIT.EXE **This was renamed because of another tool
PROGRAMS\SYSTEM\BIN\EDIT.HLP

gawk (GNU awk)
PROGRAMS\SYSTEM\BIN\gawk.exe
PROGRAMS\SYSTEM\BIN\gawk-djg.exe

GNU Diff
PROGRAMS\SYSTEM\BIN\cmp.exe
PROGRAMS\SYSTEM\BIN\diff.exe
PROGRAMS\SYSTEM\BIN\diff3.exe
PROGRAMS\SYSTEM\BIN\sdiff.exe

GNU Textutils — Collection of text utilities
PROGRAMS\SYSTEM\BIN\
    FMT.EXE
    NL.EXE
    PR.EXE
    SUM.EXE

GZip
PROGRAMS\SYSTEM\BIN\gzip.exe
PROGRAMS\SYSTEM\BIN\gzip386.exe

ispell
PROGRAMS\SYSTEM\BIN\ispell.*
PROGRAMS\SYSTEM\BIN\look.exe

mawk
PROGRAMS\SYSTEM\BIN\mawk.exe

Nano
PROGRAMS\SYSTEM\BIN\NANO.EXE
There is no included documentation, but it is Nano and has
been historically licensed as GPL. The -V flag shows:
    nano version 0.8.8 by Chris Allegretta
    (compiled 21:41:56, Mar 18 2000)
    Email:nano@asty.org Web: http://www.asty.org/nano

SLSC
PROGRAMS\SYSTEM\BIN\slsc.exe
PROGRAMS\SYSTEM\BIN\slsc.hlp
I am listing this as GPLv2 because of what is said in the 
slscdj1b\copyrite file but it could also be public domain.

UUdeview
PROGRAMS\SYSTEM\BIN\UUDEVIEW.EXE
PROGRAMS\SYSTEM\BIN\UUENVIEW.EXE

WGET.EXE
PROGRAMS\SYSTEM\BIN\WGET.EXE

xpdf converstion tools
PROGRAMS\SYSTEM\BIN\pdfdtach.exe
PROGRAMS\SYSTEM\BIN\pdffonts.exe
PROGRAMS\SYSTEM\BIN\pdfimg.exe
PROGRAMS\SYSTEM\BIN\pdfinfo.exe
PROGRAMS\SYSTEM\BIN\pdftops.exe
PROGRAMS\SYSTEM\BIN\pdftotxt.exe