AoE:  Age of Empires
BB:  Big Bertha
BRB:  Be Right Back
BSR:  Brave Sir Robin, a character in Monty Python and the Hoyl grail.  Also a forum member.
e:  energy in cost context.
e/s:  energy per second

EMG:  Energy Machine Gun
FIFO:  First in First out, as in the first think you put on this queue or stack, will be the first thing out
FILO:  First in Last out, look above, ok first thing in will be last out, so last in is first out.
Flame/Flame War :  On forums, when people start to get hostile and sometimes resort to name calling.  Causes: Religion and Politics.
LOL:  Laugh out Loud.  This is what it was back in 1997.  Some say Lots of Laughs.  What it means is I think thats really funny.
GG or gg : Good Game.  Has no real meaning.  It something you type if you lost, but don't have enough evidence the other person cheated, or if you won, it is some sort of consolation prize "I beat you ha ha, I mean gg", or used to show evidence that you aren't some pompous jerk.

gga:  good game all.
ggp:  good game partner
gga/p:  good game all, especaily partner.
LotR:  Lord of the Rings
lmao: laughin my ... off, not lamo or lame-o.
LRPC:  Long Range Plasma Cannon, as in BB and Timmy
m:  metal (maybe, particularly when dealing with cost)
mex:  Metal Extractor
MF:  MuzzleFlash, a forum member.
mm:  metal maker
mmm:  Moho Metal Maker, gives lots of metal for a big, but good price
m/s:  metal per second
Krog:  Krogoth, I can't believe I wrote that.
PC:  Either Personal Computer, or PeterC(a member of the TAU forums)
PW:  Phoenix Worx
rofl:  rolling on floor laughing, do people really do this?  I nearly fell out of my chair once, but some people abuse this
roflmao:  rolling on floor, laughing my ... off
RPN:  Reverse Polish Notation, used in calculators, especially the HP series
RPG:  Role-Playing Game, a game in which you control a character that develops.  Example D&D, and Final Fantasy
RTS:  Real Time Strategy, a game where there are no turns, everything happens real time.
solar:  solar power plant
SC:  StarCraft
TA:  Total Annihilation
TAU:  Total Annihilation Universe, a website that I frequent
TBS:  Turn Based Strategy, after you make your descisions, you click the turn button and the computer processes your turn.
Timmy:  Intimidator
VT Rocket:  Verticle Take-off rocket, used by the Merl, Diplomat, Dominator, Ranger and the Missile Frigate
UH:  UberHack.  A mod made by BSR.  
WC:  War Chicken, a forum member, who still plays TA
WC2:  WarCraft2
WCIII: War Craft 3/III
wind gen : Wind generators