NetHack:Official site. News, guides, links, and both source and executables for several platforms.
JNetHack: Version 3.2.2, Japanized. Features a new class, source, and executables.
NetHack Stuff: Dictionary, world map, and play statistics.
rec.games.roguelike.nethack Cretins Advisory: Dedicated to keeping the newsgroup clean of "spammers, d00dz and things like" that.
rec.games.roguelike.nethack FAQ: Frequently asked questions about the game, its Usenet newsgroup, and related topics.
Sascha's and Ralph's NetHack site: Includes spoilers, hints, utility programs, and a list of public NetHack servers
The NetHack Dungeon: Hall of fame, tips and tricks, spoilers, and other files for the 3.2 release.
The NetHack Home Page: Unofficial mirror site. Spoilers, source, executables, and utilities.
The NetHack Index: Annotated directory of spoilers, variants, patches, utilities, servers, reviews, and other useful information.
Yahoo! Groups - thenethacklair: Gameplay discussion group. Free membership required to participate.