Cheats and Hints

Absolute Beginner's Guide for NetHack 3.4.1 - http://www.melankolia.net/nethack/nethack.guide.html
Basic primer for new players. Does not contain spoilers.

HiSPeed's Nethack Helper - http://hispeed.tty1.com/nh-helper/nh-helper/nh-helper.html
Interactive NetHack helper mainly for item identification by price. Also includes alchemy and corpse intrinsics.

List of NetHack Spoilers - http://www.statslab.cam.ac.uk/~eva/nethack/spoilerlist.html
Collection of spoilers relevant to 3.4.3 release.

NetHack 3.4 Spoilers - http://www.spod-central.org/~psmith/nh/
Spoilers, NetHack Gazetteer, NetHack Code, Usenet FAQ, and miscellaneous help.

Ye Olde NetHack Bestiary - http://www.cim.mcgill.ca/~simra/nhtohtml/html/
Statistics on creatures encountered during gameplay.

Yet Another NetHack Site - http://www.steelypips.org/nethack/
Spoilers for versions 3.3.1, 3.4.0, and 3.41, including those posted to Usenet.