I know what the following abbreviations mean:
OMG - Oh my God
LOL - Laugh out loud (or, laughing out loud, or…)
ROFLMAO - rolling on floor laughing my as(s) off
FYI - for your information
IMHO - in my humble opinion
…and a few others I can’t think of at the moment.
But what does the following mean:
AFAIK
? Always stumps me.
As far as I know = AFAIK
Yeah that site’s great for finding out what an abbreviation stands for 
This is great information IMO. IIRC the AcronymFinder site is 
for finding out what you need.
GG game time BRB 
wtf
Not to be nitpicky, but you actually linked to a site called AcronymFinder, and then called them Abbreviations, :p, lol (laugh out loud ;)).
IIRC - now there’s another to look up! I could’ve sworn it was a type of Windows server.
phw0ar!!!
You want acronyms, play Counter-Strike online, you’ll be amazed and have no chance of keep up with the conversation 
AFAIK as far as I know
IMNSHO in my not so humble opinion
LOL lots of love (alternative meaning, not really used anymore)
BRB be right back
AFK away from keyboard
IIRC if I recall correctly
RTFM read the (fine) manual
then there’s the sort of thing you pickup from online games such as
LPB low ping *
HPB high ping *
I can’t think of others at the moment.
WTF (what the beep)
BRT (be right there)
BRB (be right back)
AFK (away from keyboard)
LOL - (Laugh out loud)
ROFLMAO - (rolling on floor laughing my as(s) off)
ROFL - (rolling on floor laughing)
FYI - (for your information)
IMHO - (in my honest opinion)
IMO - (in my opinion)
TBH - (to be honest)
YGPM - (you got private message)
OMG - (oh my god)
AFAIK - (as far as I know)
Thats all I can think of
FAO : for the attetion of.
i’ve seen this a lot on the Liverpool FC forums
IOW - In other words
grumbl nitpicking!
Ah, yes - I should have stated acronyms in my original post - it’s because I was abbreviating to “abbrev.” in my head when posting. 
As for IOW - I always thought that an expression of pain!
ie, IOW - that movie sucks!
LML = Let me Look
CYM = Check Your Mail
BBIA - Be back in awhile
STFU - Thy words wreak with ignorancy, so I recommendeth thou stoppeth thine typing
Ones I use:
LOL - Laugh out Loud
BRB - Be right Back
TTYL - Talk to you later
WTF - (I only use this occasionally)
STFU - (I only use this for laughs: example: STFU n00b!!!)
Those are the only ones I use IIRC (:p)
bbiab - be back in a bit
ATM (at the moment)