Here is a list of the abbreviations i've learned so far.
AB - Arathi Basin (battleground)/Arcane Brilliance (Mage spell)
AD - Argent Dawn
Add - Additional Target
AE - Arcane Explosion (Mage spell)
Agi - Agility
AH - Auction House
Alt - a sidecharacter, often at a lower level than your Main character)
AoE - Area of Effect
AP - Attack Power/Arcane Power (Mage talent)
AQ - Ahn'Qiraij (instance, AQ20 is the 20-men instance AQ40 the 40-men)
AV - Alterac Valley (battleground)
BB - Booty Bay
BFD - Blackfathom Deeps
BG - Battlegrounds
Blues1 - Rare items, refers to the colour-code.
Blues2 - Blizzard administrator/channel master.
Boe - Bind on Equip
BoK - Blessing of Kings (Paladin skill)
BoM - Blessing of Might (paladin skill)
BoP - Bind on Pickup
BRD - Blackrock Depts (Instance)
BRS - Blackrock Spire (Instance)
BS - Blacksmith
BWL - Blackwing Lair (Instance)¨
C- Copper
CampT - Camp Taurajo (in Barrens)
CC - Crowd Control
CoA - Curse of Agony (Warlock spell)
CoD - Curse of Doom (warlock spell)/Cash on Delivery (to pay for the item through mail)
CoS - Curse of Shadow (warlock spell)
CTF - Capture the Flag (warsong gulch)
DE - Disenchant
DI - Divine Intervention (Paladin ability)
DK/DHK - Dishonorable Kill
DKP - Dragon Kill Points
DM - Deadmines/Dire Maul (instances)
DiM - Dire Maul
DoT - Damage over Time
DPS - Damage per Second
DW - Dual Wield
EFC - Enemy Flag Carrier ( Warsong Gulch
EP/EPL - Eastern Plaguelands
FC - Flag Carrier
FFA - Free For All
FP - Flight Point/Flight Path
FTW - For The Win
G - Gold
GM - Game Master
GY - Graveyard
HK - Honorable Kill
HoT - Heal over Time
HP - Hit Points
HS - Heartstone
IAE - Instant Arcane Explosion (Mage spell)
IF - Ironforge
Imba - Imbalanced/unfair
IMO/IMHO - In My Opinion/In My Humble Opinion
Inc - Incoming
Int = Intellect
Inv - Invite
KB - Killing Blow
KDR - Kill/Death-Ratio
KEK - a horde sayingwill look like this to an alliance.
KK - to lazy to write OK.
LBRS - Lower Blackrock Spire (instance)
Leroy Jenkins -
http://video.google.com/videoplay?docid=-7714643693602998196&q=leroy+jenkins
LFG - Looking For Group
LFM - Looking For More/Members/Men
LoS - Line of Sight
LW - Leatherworker
MC - Molten Core
MD - Master Demonologist
MH - Menethil Harbor
ML - Master Looter
Mob - Enemy NPC
MT - Main Tank
Naxx - Naxxramas (instance)
NE - Night Elf
Nerf - Reduce an item/ability/class effectiveness (Nerf that Imba)
NAH - Neutral Auction House
nn - Nighty Night
OG - Orgrimmar
Ony - Onyxia's Lair (instance)
OT - Off Tank/Off-Topoc
PL - Party Leader
PPR - Points Per Run
PUG - Pick Up Group
PvE - Player versus Environment
PvP - Player versus Player
QQ - Symbol of crying, as in "Cry me a river"
Rag - Ragnaros (End Boss)
RAP - Ranged Attack Power
RFC - Ragefire Chasm (instance)
RFD - Ragefire Downs (instance)
RFK - Razorfen Kraul (instance)
S - Silver
Scholo - Scholomance (instance)
SFK - Shadowfang Keep (instance)
SM - Scarlet Monastary (instance)
SoS - Swamp of Sorrows
Spec - Specialization (what part of the talent tree is your talent points.)
SS - Southshore
Strat - Stratholme (instance)
ST - Sunken Temple (instance)
STV - Stranglethorn Vale
Sta/Stam - Stamina
Str - Strength
Spi - Spirit
SW - Stormwind
TB - Thunder Bluff
TM - Tarren Mill
Toon - A Players character in game.
TP - Teleport.
Twink - LowLv character with equipment and enchants that are overpowered for its level.
UBRS - Upper Blackrock Spire (instance)
UC - Undercity
Ulda - Uldaman (instance)
UDS - Stratholme, undead instance.
VC - van Cleef (end boss in Deadmines)
VT - Vendor Trash
WC - Wailing Caverns (instance)
WoW - World of Warcraft
WP - Western Plaguelands
WSG - Warsong Gulch (battleground)
WTB - Want To Buy
WTS - Want To Sell
XR - Crossroads
ZF - Zul'Farrak (instance)
ZG - Zul'Gurub (instance)
