General Laziness[1]
AFAIK As far as I know
AFK Away from Keyboard
AI Artificial Intelligence
ATM At the Moment
B/c Because
BRB Be Right Back
Etc et cetera = and more
FAQ Frequently Asked Questions
FFS For F***'s Sake
FYI For your Information
gg (no re) Good Game (no rematch)
GJ Good Job
GL HF Good Luck, Have Fun
IDK I don't know
IIRC If I Recall Correctly
IM(H)O In my (Honest) Opinion
k kilo = 1,000
LMAO Laughing my *** off
LOL Laugh out loud
m8 Mate
NP No Problem
Nvm Never mind
OMG Oh my Gosh
ROFL / ROTFL Rolling on the Floor Laughing
TBH To be Honest
TY Thank You
W/(o) With (out)
W/e Whatever
WTF What the F***
General AoE3
(A)TP (Advanced) Trading Post
AoC Age of Empires II Conquerors Expansion
AoE Area of Effect
AoE3 Age of Empires 3
AoEII Age of Empires II
AoK Age of Kings (AoEII was the tag name used to describe the game)
AoM Age of Mythology
AoT Age of Mythology Titans Expansion
BO Build Order
Brit British
Cav Calvary
Civ Civilization
CW Clan Wars
CW Clan Wars
DC(ed) Disconnet(ed)
DM Death match
Eco Economy
ES(O 2) Ensemble Studios
Exp / XP Experience
FF Fast Fortress
FFA Free for All
FFG For Fun Game
GGL Global Gaming League
HC Home City
HP Hit points
Inf Infantry
Jans Janissaries
LOS Line of Sight
Mercs Mercenaries
Mods Modifications of the Game
Naders Grenadiers
OP Overpowered
Otto Ottomans
Pop Population
Port Portuguese/Dock
QS Quick search
Rax Barracks
Reps/Recs Replays/Recordings
Res Resources
Rods Rodelero
ROF Rate of Fire
RTS Real Time Strategy
RTSL RTS league
SS Screenshot
TAD The Asian Dynasties expansion package
TC Town Center
TvB Tops vs. Bottoms (Top Players vs. Bottom Players)
TWC The War Chiefs expansion package
UI User Interface
UP Underpowered
UU Unique Unit
Vil Villager/Peon/Settler
WC War Chief
WW War Wagon
Xbow Crossbow
General AoE3Terms
Boom Focusing on economy, later on military
Buff To make something stronger
Card An improvement in your deck
Deathmatch Fast-pace game mode where everyone starts with 20,000 of each resource, but only lasts up to the Industrial Age
Deck The collection of improvements (cards) from your Home City.
Economy How many resources you have, how fast they are coming in etc.
Hotkey A button used instead of mouse clicking to get faster speed in game
Macro Macro management of your overall empire
Micro Micromanagement of your units (maximize what you have)
n00b / nub / newb Someone who is new to the game or possess no skills.  n00b is considered an insult by 13 year olds.  If your opponent uses this term, resign and play with a grown-up.
Nerf To make something weaker
Patch An improvement to the game
Peon Settler
Pro Someone who is considered very good at the game
Raid Bringing down enemy economy
Record Win - Lost
Rush Attack early and quick
Supremacy The standard method of playing Age of Empires 3, where everyone starts with very little resources.
Trade Route A system of trade on the map used to get up and other resources
Turtle Defensive play style
User Interface The buttons and layout of the game on the screen (i.e. the mini-map on left right)
In-Game Icons
Area of Effect
Artillery
Buildings
Cavalry
Hand or melee attack
Infantry
Attack range
Ranged attack
Ships
Siege Units
Siege attack
Treasure guardians
Villagers
Coin
Food
Wood
BBCode Reference
Bold [B]text[/B] 
Color [COLOR=color]text[/COLOR]
Changes text color. Examples: [color=red]Red Text[/color] = Red Text, [color=#FFAA55]Colored Text[/color] = Colored Text
Email Links [EMAIL]email[/EMAIL] 
Creates a mailto: link to an email address. For example, [email]johndoe@mycompany.com[/email] will give you this: johndoe@mycompany.com.
Hypertext Links [URL]url[/URL]
[URL=url]text[/URL]
The URL code lets you create a link.  For example to link to www.heavengames.com, you would use [url]http://www.heavengames.com[/url] and it would look like this: http://www.heavengames.com.
Another variant is to have text associated with the URL.  For example, [url=http://www.heavengames.com]HeavenGames [/url] would look like this: Heaven Games
ICQ Status Indicator [ICQ]icqnumber[/ICQ] 
This will return the standard ICQ indicator (the flower icon). Note that you must have the "Web Aware" option turned on in your Security/Privacy settings for this indicator to work.
Images [IMG]image URL[/IMG] 
IMG code is used for displaying images stored on other websites.  Please note that IMG tags does not work in signatures or in forums that have the tag disabled.  
Italic [I]text[/I] 
Quote [QUOTE]text[/QUOTE]
[QUOTE=user]text[/QUOTE]
[Q]text[/QE]
[Q=user]text[/Q] 
Underline [U]text[/U] 
Whisper [WHISPER]text[/WHISPER]
[W]text[/W] 
Indent [ind]text[/ind]
Bullet List item
Adds a bullet in the beginning of the line and sorts the lines into a bulleted list
  If you enclose the [*] tag within [ol] and [/ol], then you'll get a numbered list:
Superscript [SUP]text[/SUP]
Subscript [SUB]text[/SUB]
Strikeout [STRIKE]text[/STRIKE]
[S]text[/S]

[1]
NOTE:
Many gamers try to move as few body parts as possible at all time.  The acronyms save valuable seconds typing.