I agree with what anonbanon said.
My advise would be to keep it simple and broad. Deans are likely meeting with candidates from every department in the college/school that happens to be hiring at that time. One way to get a feel for this is to go to the HR web page and look at all the different departments that are hiring. Find the departments that are in the same college (or school) as psych. Multiply the number of postings you see that fit this criteria by 3 (assuming 3 candidate on campus for each position). With that number in mind, how much do you think the dean is going to remember about you? If the number is large, then not much. If you're the only one, well… you better be prepared.
This is not to say that you can totally blow off the meeting with the dean if you know s/he is busy. Regardless of how busy they are, they'll definitely remember you if you are rude, disinterested, or can't explain yourself well. Make it clear that you understand the priorities/missions of the university and that you are on board with their initiatives. If you've been involved in anything similar at your current institution, bring that up. They may start thinking about all the committees you'd be perfect for (which is what happens at my institution… and this is not necessarily a good thing). If you're really struggling, talk about how much you love the campus and how everyone you've met so far has been really nice. Positive, positive, positive. Do not talk about the crappy economy. Do not talk about how much snow there is and how cold weather sucks. Talk about how you think you fit into the university, and how your research/teaching can help the mission of the institution. Does the Psych department have a grad program? If not, is their chatter of developing one down the road? How would you be able to support this effort. If you take this approach, there will be tons of things to talk about.
Last piece of advise: Let them guide the conversation. Don't start blathering on about your research or some grant you're planning to write if the dean doesn't care (sometimes this happens). If the dean sets up the context for you to bring something up, do it. Otherwise, stick with the program.