There are many things I think I will remember from Psych 1001 five years from now. The most frequently applicable topic that sticks out in my mind is from way back at the beginning of the semester when we looked at the chapter about critical thinking and the six principles of scientific thinking... as lame as that sounds. Ruling out rival hypotheses, correlation and causation, falsifiability, simplicity (Occam's Razor), extraordinary claims, replicability- all of these things are, in a general sense, relevant on a daily basis... or at least they should be.
I don't think it was until well into my adolescence that I began really questioning the world around me. This American culture is especially good at presenting everything as fact (remember the section on pseudoscience). Imagination in the way of wondering why things are the way they are isn't entirely or overtly encouraged- even the most basic things, i.e.- why parents follow a certain system of beliefs, why school starts at 7am, why people treat other people badly, why our government is the way it is, why we all want to watch tv all the time, why Mcdonald's makes us happy, why we eat what we eat, why we can't fly etc. etc. I think the six principles are excellent lenses through which we can look at the world- and they should probably be taught from day one (though I'm sure those of you who paid careful attention to the chapter on childhood development might disagree).
They also give me a greater sense of how much I (and the rest of the world) don't know. There are so many possibilities in any (or most) situations that being very careful and thoughtful about the information we're presented with can help us keep our minds open and fair.