Angband Acronyms

General

AFAICT: As Far As I Can Tell
AFAIK: As Far As I Know
AI: Artificial Intelligence
ASCII: American Standard Code for Information Interchange (often used to refer to pure text mode)
BTW: By The Way
compo: competition
FAQ: Frequently Asked Questions
FYI: For Your Information
HAND: Have A Nice Day
HTH: Hope That Helps
IIRC: If I Recall Correctly
IMHO: In My Humble Opinion
IMO: In My Opinion
LOL: Laughing Out Loud
newbie: newcomer, beginner
OTOH: On The Other Hand
ROFL / ROTFL: Rolling On (The) Floor Laughing
spoiler: Information about the game which "spoils" the fun, general name used about help files which are not distributed with the game
TIA: Thanks In Advance
Tk: Tool Kit (programming package for user interfaces and graphics)

Angband specific

Borg: Automatic (computer controlled) player
DSM: Dragon Scale Mail
FA: Free Action
GoI: Globe of Invulnerability
HA: Holy Avenger
OoD: Orb of Draining
PDSM: Power Dragon Scale Mail
Phial: Phial of Galadriel
RGRA / r.g.r.a: rec.games.roguelike.angband
RLL: Potion of Restore Life Levels
RNG: Random Number Generator / Random Number God
RoS: Ring of Speed
WoR: Word of Recall
YAAD: Yet Another Annoying Death
YACD: Yet Another Character Dump
YAFM: Yet Another Funny Message
YASD: Yet Another Stupid Death / Yet Another Silly Death
YASM: Yet Another Stupid Move / Yet Another Strange Message / Yet Another Silly Message
YAWP: Yet Another Winner Post

Variants

The acronyms for variants are often used in the subject of a message enclosed in squared brackets (for example [Z]) to define what variant the poster is talking about (so a [Z] in the subject-line means that the post is about ZAngband).

CatH: CatHAngband
Cth: CthAngband
Dr: DrAngband
Ey: EyAngband
GSN: GSNAngband
GW: GWAngband
K: KAngband
Kam: KAmband
M: MAngband
O: OAngband
Pern: PernAngband
Psi: PsiAngband
Pzi: PziAngband
R: RAngband
V: Vanilla Angband, the good old standard Angband
Z: ZAngband
ZTk: ZAngbandTk

People

APW: Andrew P. White
DvE: Dennis van Es
GSN: Gwidon S. Naskrent
LM: Leon Marick
RAK: Robert Alan Koeneke
RML: Ross Morgan-Linial
RR / rr9: Robert Ruehlmann
TY: Topi Ylinen

Interesting links

Roguelike Game Jargon - List of acronyms used in roguelike games (some of the entries have been duplicated here).
New Hacker's Dictionary - Detailled explanations of the hacker jargon, including entries for Angband (with a link to Thangorodrim!) and the Random Number God.