We have an hour and a half session with our Special Program For First Year Students students a day or two before real classes begin. Because some students won't be able to be there, we're not supposed to cover any course content that would put those students behind. But we're supposed to give the students some meaningful experience. Keep in mind that the students have moved into the dorms and been inundated with new information, and that they'll continue to be inundated and overwhelmed for at least the first three weeks of classes.
Here's what I generally do in those first 90 minutes:
I usually spend some time trying to begin learning names (and to get them to begin to learn each others' names). And then I talk about what a syllabus is, and how to read it.
I introduce my mentors, and they do a short intro to campus life.
And I tell them that they should never, having missed class, ask a professor if s/he said anything important. (At which point I have them exchange email/phone information with several other students so that they can email or call ahead of time to get a rundown of what happened in class.)
And I tell them that it drives instructors nuts when a student walks into a class and stands in front of the professor at the beginning of class (while 30+ other people wait) and expects the professor to solve a problem the student had with not being able to print out his/her homework just before class. (At which point I suggest that planning ahead so that you have time for computer disasters is a great idea when you can. And when you can't, the world won't end, probably.)
This semester, I'm also planning to get extra copies of the local "what's happening in town this month" newspaper and handing them out.
Imagine your first 90 minutes of class with new first year students no "content"); what would you want to do or talk about?