Emoticons:

:) = Happy face for humor, laughter, friendliness, sarcasm
:D = Super happy/toothy smile, broad smile, etc.
:( = Sad face for sadness, anger, upset 
;) = Wink 
:/ = Wry face 
:P = Tongue out for just kidding 
(((hug))) = a hug 
< g > = grin 
ALL CAPS = yelling 

Phrases:

AFO = Adult fan of
AIM = AOL Instant Messenger 
ASAP = as soon as possible 
ATM = at the moment 
AYT = are you there?
B = bye
BBFN = bye bye for now
BBL = (I will) be back later
BYO = Bring your own
CU = see you
DDG = Drop dead gorgeous
EA = e-mail alert
EOD = end of day
ETA = estimated time of arrival
Flame(s) = negative or derogatory e-mail or chatting
FYI = for your information
GTG = got to go
ICQ = 1) I seek you 2) a messaging service
IGU = I give up
IMO = In my opinion
IRT = In regards to
JAM = Just a minute
JIT = just in time
jj= just joking
jk = just kidding 
LMHO = Laughing my head off
LOL = laughing out loud
Lurk = hang out in the background/viewing
L8R = later
NA = not acceptable/applicable
NOS = new old stock
OIC = Oh, I see 
POV = point of view
PS = post script
QR = quick response 
ROTFLOL = rolling on the floor laughing out loud
SMS = Short message service (an e=mail or other message)
SPAM = unwanted e-mail or chat content
SRO = standing room only
Sup = what's up?
Tom = tomorrow
TNX or TKS = thanks
TTYL = talk to you later
U2 = you, too
UR = you are
VSTR = VoiceStream
WYSIWYG = What you see is what you get

Abbreviations for words:

1 = one, won, want
2 = To
4 = for
8 = ate
Y= why
M = am
N = and
M8 = mate, boy or girl friend
NE = any
R = are
U = you
O = oh
K = OK
L8R = Later
4VR = forever
YER = your
B4 = before
Cuz = Because

Examples of text-speak:

i12cu = I want to see you
c u l8r k? = see you later, ok?
10SNE1 = Tennis anyone?

VoiceStream Wireless