Some common cyberslang:

BRB - Be Right Back
BTW - By The Way
FAQ - Frequently Asked Questions
Flame - To send nasty or insulting messages
GMTA - Great Minds Think Alike
Gremlin - Annoying bugs in computer programs
IMHO - In My Humble Opinion
IMNSHO - In My Not So Humble Opinion
JOOTT - Just One Of Those Things
L8R - Later
LOL - Laughing Out Loud
Lurking - Signing onto chat channels or mailing lists but not participating
Luser - Where loser and user meet such as, "Did you see that luser's lame
        home page?"
Netizen - Internet citizen
Net head or Web head - a person who is on the Internet a lot
Open Collar Worker - a person who works from home
ROTFL - Rolling On The Floor Laughing
RTM - Read The Manual
Snail Mail - Sending information through the US Postal Service
Spam - uncolicited junk E-mail
Spoofing - When someone tries to masquerade as someone else, usually used in
        hacking