I don't know of a location for them all, but here's a few:
OT = off topic (not directly related to decorating, on this board)
Pic= photo/picture
LOL= laughing out loud
ROFLMAO= rolling on the floor laughing my a$$ off!
DH= Dear Hubbie
DD= Dear Daughter
DS= Dear Son
DDIL= Dear Daughter-in-Law

Also,
SW = Sherwin Williams
RH = Restoration Hardware
BM = Benjamin Moore
EK = Ellen Kennon

JMHO= just my humble opinion . . . or this version:
IMHO= In my humble opinion
OMG= Oh my gosh! . . . at least when I use it, it does ;^P

I used to think that GFY meant "good for you" until I was told otherwise. ;( LOL

ROFLMAO, Parma!!!!

IIRC = If I remember correctly
IRL = In real life
NP = no problem
OP = original poster
PO = previous owner
CL = Craigslist

How about the ones that are specific to decorating? Such as...

PO = Previous Owner
ORB = Oil Rubbed Bronze
SW = Sherwin Williams (paint)
BN = Benjamin Moore (also paint)
EK = Ellen Kennon (still more paint)
ID = Interior Designer
CL = Craigs List
HD = Home Depot
LR, DR, BR = Living Room, Dining Room, Bedroom
SS = Stainless Steel
JMHO = Just My Humble Opinion

F&B = Farrow & Ball
IYKWIM = If you know what I mean
MBR = Master bedroom

parma it took me a moment with GFU! duh.
My DH teases me that DH really means Dumb Husband in GW code.
On the kitchen forum DW means either dishwasher or Dear Wife, ya gotta read closely sometimes there.
DD dear daughter
DS dear son
etc.

Last weekend the neighbors were discussing using abbreviations when they text their kids. The kids all claimed they didn't know what the moms meant and the moms must have been making up their own abbreviations (which they did admit to doing!).
A teacher in the group suggested putting flash card type labels on all sorts of things around the house. Then when Mom texts "empty dw" the kid will know it means dishwasher & can't avoid the task by playing dumb.
FWIW (for what it's worth)

That would be mt dw

In my college Sociology course there was actually a chapter on this.

SS also stands for Silver Sage
You'll see lots of common paint colors abbreviated such as:

BM BT: Benjamin Moore Baby Turtle
SW RG: Sherwin Williams Restrained Gold
RH SS: Restoration Hardware Silver Sage
ROFLMFAO: Rolling On Floor Laughing My Fat A!@ Off

Great thread - very helpful!

I would like to nominate a new one:
DK: Darling Kitty or D*** Kat, depending on, well a lot of things which you will understand if you are a cat lover.

TS - Thrift Store
GS -Garage Sale

Since someone asked in another thread....

WT = window treatments

Also:

EC = entertainment center

HWF = hardwood floors

GW = GardenWeb.com

Thanks everyone. Parma, that's sooo funny! I would have thought the same thing - lol!