I don't often use sms-ese, but when I do, I BTW. BTW = by the way FTW = for the win!! :D The there's WTF = what the f***!! (for disbelief)

It means "By the way".

In American chat, email, etc., there is also: LOL = Laughing Out Loud LMAO = Laughing My Ass Off LMFAO = Laughing My F*ckng Ass Off ROFLMFAO = Rolling On Floor Laughing My F*cking Ass Off SMH = Shakes My Head IMHO = In My Humble Opinion

by the way for the win :)

Great answers. I suggest you have a look at the site www.tacatest.com It contains a very useful list of acronyms.