With this major mode editing NetHack's special level description files is much easier in emacs. Map characters can be highlighted in correct colors, keywords are highlighted, you can get the coordinates inside maps, and keywords can be autocompleted.
This perl script will create a html page with links to all NetHack's functions in it. Example page for NetHack 3.4.3
You probably want to generate html crossreferences with cxref or something like that so that the links work correctly.
This zip package contains precompiled NetHack v3.4.3 for Windows, with menucolors patch applied. Includes both TTY and Windows GUI versions. (nethack.exe and nethackW.exe) Menucolors is compiled WITH regexp.
With links to nethack.wikia.com.
This script allows you to view some screenshots to compare how different tilesets look like, and this one allows comparison of individual tiles.