How's it going? How's everything? How's life?

(This means "How are you?" not "Where are you going?")

Asking about present activities

What's up? What's happening?

(What are you doing now?)

Asking and telling about recent events

What's new? Guess what?

(What interesting has happened since I last saw you?) (I want to tell you something. Ask me about it.) (The appropriate response to this is "What?") A: Guess what? A: I just got a new job. B: What? B: Congratulations!