I've seen several threads in the past wondering what a certain abreviation meant, look no further! All your questions can be answered here.
(Spoilered because it's rather long.)
! AFAIC as far as I'm concerned
AFAICR as far as I can recall
AFAICT as far as I can tell
AFAIK as far as I know
AFAIR as far as I recall
AFAIU as far as I understand
AFD away from desktop
AFK away from keyboard
AFW away from window
AIU as I understand
AIUI as I understand it
AKA also known as
ASAIC as soon as I can
ASAP as soon as possible
ATM at the moment
AWOL absent without official leave
AYBABTU all your base are belong to us
AYT are you there
B/C because
B/W between
BBIAB be back in a bit
BBL [I'll] be back later
BBS be back soon
BBT be back tomorrow
BIAB back in a bit
BIAF back in a few
BIALW back in a little while
BIAS back in a second
BIAW back in a while
BOGAHICA bend over, grab ankles, here it comes again
BOHICA bend over here it comes again
BRB [I'll] be right back
BS bulledit
BTDT been there, done that
BTTH boot to the head
BTW by the way
CMIIW correct me if I'm wrong
CNP continued [in my] next post
COB close of business [day]
COTS commercial off-the-shelf
CYA see you around
D/L download
DIY do it yourself
DKDC don't know, don't care
DSTM don't shoot the messenger
DTRT do the right thing
DTWT do the wrong thing
DWIM do what I mean
EG evil grin
EMSG email message
EOB end of business [day]
EOD end of discussion
EOL end of life
ETLA extended three letter acronym
EWAG experienced wild-ass guess
FAQ frequently asked question
FCFS first come first served
FOAD fall over and die
FSDO for some definition of
FSVO for some value of
FUD fear, uncertainty and doubt
FWIW for what it's worth
FYI for your information
G grin
G/C garbage collect
GAC get a clue
GAL get a life
GIGO garbage in, garbage out
GMTA great minds think alike
GTG got to go
HAND have a nice day
HHIS hanging head in shame
HICA here it comes again
HTH hope this helps
IAC in any case
IANAL I am not a lawyer
IC I see
ICBW I could be wrong
ICCL I couldn't care less
IHBW I have been wrong
IIANM if I am not mistaken
IIRC if I recall correctly
IIUC if I understand correctly
IMAO in my arrogant opinion
IMCO in my considered opinion
IMHO in my humble opinion
IMNSHO in my not so humble opinion
IMO in my opinion
IOW in other words
IRL in real life
ISAGN I see a great need
ISTM it seems to me
ISTR I seem to recall
ITYM I think you mean
IWBNI it would be nice if
IYSS if you say so
J/K just kidding
JHD just hit ``delete''
JIC just in case
JK just kidding
JMO just my opinion
JSYK just so you know
JTLYK just to let you know
KISS keep it simple, stupid
KITA kick in the ass
KNF kernel normal form
L8R later
LART luser attitude readjustment tool (ie, hammer)
LBNL last but not least
LJBF let's just be friends
LMAO laughing my ass off
LMSO laughing my socks off
LOL laughing out loud
LTNS long time no see
MIA missing in action
MOTAS member of the appropriate sex
MOTOS member of the opposite sex
MOTSS member of the same sex
MTF more to follow
MYOB mind your own business
N/M never mind
NBD no big deal
NIH not invented here
NMF not my fault
NMP not my problem
NOYB none of your business
NP no problem
NRFPT not ready for prime time
NRN no reply necessary
OIC oh, I see
OMG oh, my god
OT off topic
OTL out to lunch
OTOH on the other hand
OTT over the top
OTTOMH off the top of my head
PEBKAC problem exists between keyboard and chair
PFY pimply faced youth
PITA pain in the ass
PKSP pound keys and spew profanity
PNG persona non grata
PNP plug and pray
POC point of contact
POLA principle of least astonishment
POLS principle of least surprise
PPL pretty please
PTV parental tunnel vision
QED quod erat demonstrandum
QFE quoted for emphasis
QFT quoted for trolling
RFC request for comments
RIP rest in peace
RL real life
RLC rod length check
ROFL rolling on floor laughing
ROFLMAO rolling on floor laughing my ass off
ROTFL rolling on the floor laughing
RP responsible person
RSN real soon now
SCNR sorry, could not resist
SEP someone else's problem
SHID slaps head in disgust
SIMCA sitting in my chair amused
SMLSFB so many losers, so few bullets
SMOP simple matter of programming
SNERT snot-nosed egotistical rude teenager
SNMP sorry, not my problem
SNR signal to noise ratio
SO significant other
SOP standard operating procedure
SSIA subject says it all
SUS stupid user syndrome
SWAG silly, wild-assed guess
SWAHBI silly, wild-assed hare-brained idea
SWMBO she who must be obeyed
TANSTAAFL there ain't no such thing as a free lunch
TBC to be continued
TBD to be {decided,determined,done}
TBOMK the best of my knowledge
TFPC trolling for post count
THNX thanks
THX thanks
TIA thanks in advance
TINC there is no cabal
TLA three letter acronym
TLB translation lookaside buffer
TMA too many abbreviations
TMI too much information
TNF The NetBSD Foundation
TOEFL test of english as a foreign language
TPTB the powers that be
TRT the right thing
TTBOMK to the best of my knowledge
TTFN ta ta for now
TTYL talk to you later
TWIAVBP the world is a very big place
TY thank you
TYVM thank you very much
U/L upload
UTSL use the source, Luke
VEG very evil grin
W/ with
W/O without
WAG wild-ass guess
WB welcome back
WFM works for me
WIBNI wouldn't it be nice if
WIP work in progress
WOMBAT waste of money, brain, and time
WRT with respect to
WTH {what,where,who,why} the hell
WYSIWYG what you see is what you get
YALIMO you are lame, in my opinion
YHBT you have been trolled
YHL you have lost
YKWIM you know what I mean
YMA yo momma's ass
YMMV your mileage may vary
YW you're welcome
((I'd be nice if a mod would sticky this. Thanks.))