AFK = away from keyboard
ASL or A/S/L = Age Sex Location
BBL = be back later
BRB = be right back
BTW = by the way
CUL8R = see you later
FAQ = frequently asked question
FWIW = for what it's worth
FYI = for your information
GTSY = good to see you
IMHO = in my humble opinion
IOW = in other words
LOL = laughing out loud
LTNS = long time no see
OTOH = on the other hand
ROFL = rolling on the floor laughing
THX = thanks
TIA = thanks in advance
TTFN = ta ta for now
TTYL = talk to you later
WB = welcome back