If you're interviewing for a tech or web job and you want to show examples of your work, it's fine to bring your laptop or iPad to show the interviewer what you have accomplished.
What shouldn't you bring? Don't walk into a job interview with a coffee cup or bottle of soda or water or anything else to eat or drink. Don't chew gum.
Your cell phone should be turned off and out of sight. You don't want to be the applicant whose text messages or calls disrupted the interview.