Found a few from wikipedia, knew about half from before but there are ridiculously many
# AFAIK: as far as I know
# ASAP: as soon as possible
# ATM: at the moment
# B&H: Bitches and Hoes
# Bai2u: 'bye to you' goodbye
# BBIAB: be back in a bit (used to express a longer time of absence than with brb)
# BBL: be back later
# BBS: be back soon
# BRB: be right back or bathroom break (very commonly used)
# BTW: by the way
# Bump: used in forums to bring a post to the top of the forum list (a common backronym for "bring up my post")
# CYA: see ya, or see you later (also CU) (or, less commonly and depending on the context, cover your ass)
# DMY: don't mess yourself (used to tell someone they are overreacting, seen on The Simpsons as a spoken abbreviation)
# DND: do not disturb
# DW: Don't Worry
# EB: eyeball, meaning to meet in personal/in real life
# F2P: free to play
# FFS: for fuck's sake
# FTL: for the lose (used to dislike something)
# FLToG: For the love of God
# FTW: for the win (used to express enthusaism or approval) (Less commonly known as "Fuck the world")
# FU: Fuck you
# FYI: for your information
# FYSIWALOL: finding your saying interesting without actually laughing out loud
# G2G or GTG: got to go or good to go
# GD: god damn
# GG: good game or good god
# GF: Good Fight
# GFYS: Go fuck yourself
# GJ: Good Job
# GL: good luck
# GLF: Group looking for ___ (used mostly in MMORPGs)
# GN8: good night
# GS: GameSpot.com
# GTFO: Get the fuck out
# GTH: go to hell
# GOOMH: Get Out Of My House
# GLLN: Got Laid Last Night(?)
# Hai2u: 'hi to you' hello
# HOMG: Ho my God
# HTH: hope that helps or happy to help
# IANAL: I am not a lawyer (used when offering amateur commentary on a legal case)
# IAS: I am smiling (not quite "lol")
# IDK: I don't know
# IIRC: if I recall/remember correctly
# IMO: in my opinion
# IMHO: in my humble/honest opinion (derived from IMO or vice-versa)
# IRL: in real life
# JIC: just in case
# JK: just kidding
# JM: Jaman (for Ja Mann - n1 Slang)
# JW: just wondering
# KIT: keep in touch
# KK: okay
# kthxbye: Shorter, and faster, way of saying "Okay. thank you. Good bye".
# Lag: where a connection is not as fast as others making the game lag behind
# L33t: elite
# LFG: looking for group (used mostly in MMORPGs)
# LFT: looking for team (used mostly in MMORPGs)
# LOL: laugh out loud
# LMAO/LMFAO: Laughing my (fucking) ass off
# LMIRL: Let's Meet In Real Life
# L2P: learn to play
# LYLAS: love you like a sister
# MOFO: MotherFucker
# MYOB: mind your own business
# nOOb: Newbie, often one who dies alot in their first few times in games online
# N1: nice one
# NE1: Anyone
# NIFOC: Naked In Front Of Computer
# NP: no problem
# NS: nice shot (Commonly used in Gunbound)
# NSS: no shit sherlock
# NT: nice try (Commonly used in Gunbound)
# NVM: nevermind
# NSFW: not safe for work (often used as a warning that a link contains racy or pornographic images)
# NWS: not work safe
# OAC: Only At Crooms
# OMG: oh my god
# OMFG: Oh My Fucking God/Sh
# OMGWTFBBQ: combines the terms OMG, WTF, and BBQ. (can also be used as a mockery of newbies who express surprise at commonly known facts, a mockery of L33T, or in self deprecation)
# OMW: on my way (usually used in ORPGs)
# OH NOES: oh no (commonly a mockery of stupidity or of L33T
# OP: original post/original poster (referring to the first post in a thread on a forum)
# OTOH: on the other hand
# ORV: orita vengo (used in Spanish)
# P2P: pay to play, player to player, or peer to peer
# P2V: penis to vagina (referring to sex)
# PK(er): Player kill(er)
# PVP: Player vs. Player
# PVE: Player vs. Enemy/Environment
# PWN(d): own(ed). Usually referring to someone in a video game being decidely beaten by another player.
# PEBKAC: problem exists between keyboard and chair
# PO: piss off
# POS: Parent Over Shoulder
# PO'd: pissed off
# QFT: quoted for truth; sometimes also means quit fucking talking
# QQ: cry more (meant to look like eyes with tears dripping from them)
# QT: cutie
# RE: returned or back or rematch
# RM: remake
# RIFK: See ROFL. Originally a typing error of ROFL, it is now puposely used in place of ROFL. Some, however, refer to it as Rolling In the Floor Kicking (But you can't roll IN a floor, can you?). Others say it is Rolling In teh Funneh Kookies (which doesn't make sense either).
# ROFL: rolling on floor laughing
# ROFLCOPTER: retardation of ROFLMAO
# ROLFCOPTER: even bigger retardation of ROFLMAO (rolling on "laughing" floor)
# ROTFL: rolling on the floor laughing
# ROTFLM(F)AO: rolling on the floor laughing my (fucking) ass off
# RTFM: read the fucking manual
# SAOM: shitting all over myself (alternative to ROFL)
# SGTM: Silently giggling to myself
# SFW: safe for work
# SIF: As if
# SU: shut up
# STBY: Sucks to be you
# STFU: shut the fuck up
# STFUPPERCUT: shut the fuck upper cut!
# SNAFU: Situation Normal, All Fucked Up!
# STHU: shut the hell up
# TBA: to be added or to be announced
# TBH: to be honest
# TK(er): Team Kill(er)
# TT4N: ta ta for now
# TTYL: talk to you later
# TTYS: talk to you soon
# TY: thank you
# TYVM: thank you very much
# THX: thanks
# YW: you're welcome
# WB: Welcome back
# W/E(W\E)(W.E)(WE): whatever
# WD: Well done
# WS: work safe
# WTH: what the heck/hell
# WTB: want to buy
# WTG: way to go
# WTF: what the fuck
# WTFPWN(D): An exaggeration of PWN(D), usually referring to the element of surprise or the hugely unfair elements involved.
# WTS: what the shit or want to sell
# WTT: want to trade
# WTV: watching tv
# WUU2: what you up to
# WU@: what/where you at
# ZOMG: variant of OMG, taken from a typo of hitting the 'z' next to the left shift (typically when very excited)
http://en.wikipedia.org/wiki/Internet_slang