How are you?
How's it going?
What's up? (info)
What's going on?
Greetings for various times of the day.
Greeting for a person you haven't seen in a long time.
I haven't seen you in years!
Long time no see!(info)
Expressing surprise at meeting someone.
What a surprise to meet you here!
Fancy meeting you here!
Never thought I'd see you here!
After you have greeted someone.
Haven't we met before?
Didn't we meet at that party last year?
I'm sorry! I have forgotten your name.