NetHack (see the Official NetHack Home Page for more information) comes with a lot of documentation, both publicly available and secret. The database is the most comprehensive of all these; it gives away a lot of information on things in the game.
The NetHack Docs are fully cross-referenced versions of the documentation and data files that come with NetHack. All words in the Docs that appear in the database are changed to links to that entry in the database. That includes all words in the database itself. It allows you to start reading in any document, and find out what the database has to say about it; you might be surprised about how complete the information actually is!
The files below are split into three sections, the documents, the public datafiles and the private datafiles. The documents are the files that are distributed with NetHack; everyone can read these. The public datafiles are the files that are randomly accessible from within the game; reading them from top to bottom might be considered a spoiler, though. The private datafiles are not randomly accessible and are therefore definitely spoilers.
Note that all references (links) point to the database, which is a public datafile.
The NetHack Docs were created with nhdat2html, a Perl program written by me that parses the database, changes the entries into regular expressions and searches for those to change them into links. That means occasionally a link may be incorrect; the program only knows what a word looks like, not what it means.Still I am interested in any errors that you find; please write me an e-mail if you encounter any.
If anyone is interested in the ugly source code for it, drop me an e-mail also. The source code is available under the NetHack License.
nhdat2html was inspired by vim2html, a similar utility that cross-references the files that make up the Vim manual.