You should select a topic that interests you and that you feel you have a good command over. Perhaps something from your dissertation work (or other research) would be useful here? It's critical to select the topic wisely so that you can speak clearly and naturally about the material. Also, consider how much time you'll have. If you're given 45 or 50 minutes, you can cover quite a bit more than if you're given 25 or 30 minutes. That said, some example topics from social psych that might be good include… conformity, self-esteem, persuasion, etc. I'd suggest sticking to one well-known topic and then provide both an articulate, concise overview of the material - but - then incorporate some findings from recent research to liven things up.
Also, be sure you use a good format for your talk. Since you're interviewing at a SLAC, they'll be looking for your capability to interact with the audience. If you just stand up in front of everyone and lecture, it might not go over well. Try to draw-in audience members with some participation. Asking some sort of open-ended question to preface your talk or having some sort of demonstration/activity may help. The danger with such attempts is that if your audience is pretty flat to begin with, you might get no interaction (I had this happen with one research talk presented to undergrads and faculty at one institution).
Things to avoid… the obvious like reading from notes or lecture slides, standing like a statue behind some podium, and not practicing your talk timing in advance. Be sure to leave 5 minutes or so for questions at the end of your teaching talk, too. Also, hand-outs are not worthwhile - they're just distracting.
Things to try… incorporate some multimedia into your presentation. YouTube is great for this (just screen the videos in advance!).