Not mad or not mean. Used after messages or posts over text to indicate tone.

Not Much. Mostly used on im (instant messaging) e.g msn, aim, skype.

perfect way of killing a conversation.

Short for "Not Mind Safe" (and not for "Not My Style", what kind of lame "street" phrase is that anyway). Indicates content that so disturbing it should be forever left unseen. Used as an extreme warning for images whose full horror is not covered by NWS (Not Work Safe).

an annoying/lazy way of saying "Oh, I was just sitting here with my thumb up my ass, waiting for you to ask me what I was doing. In fact, let's just stand here and piss away 3 minutes of our lives talking in unclear ambiguous terms about how our day is, what we did five minutes ago, and what we plan on doing five minutes from now."

An abbreviation of "not much" or "nothing much". It is most commonly used in instant messaging conversations as an easy and thoughtless answer to the question what's up.

Some people also use it as an abbreviation for "nevermind", but "nvm" is more popular.