im guessing most interweb literate people probably know most of these, but just in case they don't
AFK: away from key bored
BTK: back to key bored
noob: computer literate people, often speak in leet, also called N00B, not to be confused with newb
Newb: a newbie
Spammers: people who repeat and just spam often nonsense
Trolls: people who go around and be cruel and rude for no reason
Leet: 74lk1ng l1k3 7h15 (translated: using numbers and symbols in place of letters)
WTF: what the F*** ( also WTH being the same but with hell, and wtfh, but im sure you can get the rest of this)
FTW: for the win
bbl: be back later