More than you ever wanted to know (or FMTYEWTK, for short)

. . .
Abbreviation Meaning
404 I haven't a clue
ADN Any day now
AFAIK As far as I know
AFK Away from keyboard
ASAP As soon as possible
A/S/L? Age/sex/location?
B4N Bye for now
BAK Back at the keyboard
BAS Big a** smile
BBL Be back later
BBN Bye bye now
BBS Be back soon
BEG Big evil grin
BF Boy friend
BFD Big f***ing (freaking) deal
BFN Bye for now
BG Big grin
BL Belly laughing
BMGWL Busting my gut with laughter
BOTEC Back-of-the-envelope calculation
BRB Be right back
BTA But then again...
BTDT Been there, done that
BTW By the way
BWL Bursting with laughter
BWTHDIK But what the heck do I know...?
C&G Chuckle and grin
CNP Continued in next post
CRB Come right back
CRBT Crying real big tears
CU See you
CUL See you later
CUL8ER See you later
CYA See ya
CYA Cover your a$$
CYO See you online
DBA Doing business as
DL Dead link
DLTBBB Don't let the bed bugs bite
DIKU Do I know you?
DOM Dirty old man
DOS Dozing off soon
DQMOT Don't quote me on this
DTRT Do the right thing
DWB Don't write back
EG Evil grin
EMFBI Excuse me for butting in
EMSG E-mail message
EOM End of message
EOT End of thread (meaning: end of discussion)
ETLA Extended three-letter acronym (that is, an FLA)
F2F Face to face
FAQ Frequently-ask question(s)
FC Fingers crossed
FISH First in, still here
FLA Four-letter acronym
FMTYEWTK Far more than you ever wanted to know
FOMCL Falling off my chair laughing
FTBOMH From the bottom of my heart
FUD Fear, Uncertainty, and Doubt
FWIW For what it's worth
FYI For your information
G Grin
GA Go ahead
GAL Get a life
GD&R Grinning, ducking, and running
GF Girlfriend
GFN Gone for now
GIWIST Gee, I wish I'd said that
GL Good luck
GMAB Give me a break
GMTA Great minds think alike
GOL Giggling out loud
GTRM Going to read mail
GTSY Glad to see you
H&K Hug and kiss
HAGN Have a good night
HAND Have a nice day
HHIS Hanging head in shame
HIG How's it going
HT Hi there
HTH Hope this helps
IAC In any case
IAE In any event
IANAL I am not a lawyer (but)
IC I see
IHA I hate acronyms
IHU I hear you
IIRC If I recall correctly
ILU or ILY I love you
IM Immediate (INSTANT) message
IMCO In my considered opinion
IMHO In my humble opinion
IMing Chatting with someone online
IMNSHO In my not so humble opinion
IMO In my opinion
IMS I am sorry
IOW In other words
IRL In real life (that is, when not chatting)
ITIGBS I think I'm going to be sick
IWALU I will always love you
IYSWIM If you see what I mean
J4G Just for grins
JIC Just in case
JK Just kidding
JMO Just my opinion
JTLYK Just to let you know
KISS Keep it simple stupid
KIT Keep in touch
KOTC Kiss on the cheek
KOTL Kiss on the lips
KWIM? Know what I mean?
L8R Later
L8R G8R Later gator
LD Later, dude
LDR Long-distance relationship
LHO Laughing head off
LLTA Lots and lots of thunderous applause
LMAO Laughing my a** off
LMSO Laughing my socks off
LOL Laughing out loud
LSHMBH Laughing so hard my belly hurts
LTM Laugh to myself
LTNS Long time no see
LTR Long-term relationship
LY Love ya
LY4E Love ya forever
MorF Male or female
MTF More to follow
MUSM Miss you so much
NADT Not a darn thing
NP or N/P No problem
NRN No response necessary
OIC Oh, I see
OLL Online love
OMG Oh my God
OTF Off the floor
OTOH On the other hand
OTTOMH Off the top of my head
PANS Pretty awesome new stuff (as opposed to "POTS") PAW Parents are watching
PDA Public display of affection
PITA Pain in the a**
PM Private message
PMFJIB Pardon me for jumping in but...
POAHF Put on a happy face
:: POOF:: Goodbye (leaving the room)
POTS Plain old telephone service
PU That stinks!
QT Cutie
RL Real life (that is, when not chatting)
ROR Raffing out roud (Engrish for "laughing out loud") ROTFL Rolling on the floor laughing
ROTFLMBO Rolling on the floor laughing my butt off
RPG Role-playing games
RSN Real soon now
RT Real time
RTFM Read the f***ing (fine) manual
RYO Roll your own (write your own program; derived from cigarettes rolled yourself with tobacco and paper)
more coming