It's not quite as common nowadays, but you never know if you’ll be asked for identification, so it's worth bringing anyway.  When in doubt, ask the person who set up your interview in advance — better safe than sorry!

As a job seeker, business cards are great for networking and interviewing.  Give your card to your interviewer, or anyone else you talk to about the job. 

Odds are, you wouldn't leave the house without it anyway, but make sure to bring your phone with you so you can enter the directions to your interview location, especially if you’ve never been there before.   On your phone's notepad app, or on the directions you've printed out, write

out the name and contact information of your interviewer(s). This way, if something does go wrong on your way to the interview, you can let them know. This will also help ensure that you don't forget your interviewer's name — a major faux pas.

Print out a few copies of the most updated version of your resume.  You should also have extra copies in case you need to reference it during the interview — or if extra interviewers show up.

You may be used to taking notes on your laptop or phone, but in interviews, it definitely looks better if you have paper and a pen handy to jot down notes like people to contact, addresses or anything else mentioned in the interview that you want to remember later. 

This can be a folder, binder or even a website shown on your tablet. Your portfolio should be organized in a way that makes it easy to reference during your interview. The contents of your portfolio will depend on your profession, but there should be quality examples of your work and accomplishments.

Bring an updated list of your references. Your interviewer may or may not ask for these, but again, it’s best to be over-prepared.  The list should have at least three professional references, along with how they know you and how to contact them.

you've done research, so your interviewer can see your true interest in the position.