Etiquette : If your manager didn't introduce you to the people at office?

In the kitchen or elevator or anywhere you aren't just quickly ping by, you simply stick out your hand for a shake and say, "I'm kind of new in this office and wasn't able to meet everyone. I'm X, I'm working in the X Dept." Hopefully they will respond with their own name and place. If not, just ask "...and may I ask your name?" If you're walking down the corridor/hall and are about to p someone you don't know the name of but know enough about to think you may need to know their name in the future (like a peer or a higher boss), if they are looking you in the eye you can slow down and mention that you haven't been introduced yet, you're X. But if the other person looks like they are trying to get somewhere fast, or has other things on his/her mind, or isn't at all interested in you (like, you might as well be invisible), just let them p without saying anything (maybe just a quick hello you don't expect a reply to) and reserve meeting them for later. Later when you get the chance, you can introduce yourself, mention you noticed them in a hurry in the hall and you didn't want to detain them. It'll say you are intuitive to other people and have good judgment.