In 5 years I think the two concepts that will still stick out to me the most will be "Personality" and "Memory".
I know that what I learned about personality will stick with me for a long time. Especially after the lab we did, where we were separated into 4 groups based on our personalities. It was so strange how spot-on we were to the "norms" for each group type. I even remember calling my mom later that night and telling her about lab because I thought it was so interesting. It is really astonishing to think that we can be put in these groups and because of our personality we will act a certain way (with some variation because everyone is different and it is more complex than that). It was also really fun to learn about each type of personality and see where I fit in.
I feel that the other big concept I will remember is Memory, just because it has always interested me. It may not be the easiest subject to learn about, but by far one of the most interesting. How the brain remembers lists, schedules, etc. is so fascinating and the fact that you can only usually remember 7 things in a list plus or minus a couple is absolutely crazy. When we did the lab with the lists, I found that for each list I could only remember 7 things without fail. Also, the fact that your brain will add words to a list that are similar to the other words is very interesting.That MUST explain why when I go to Target for one thing, I end up with a cart full of random stuff. :)
Overall, even though Psychology isn't the easiest subject to learn about it is really one of the most interesting subjects I have had at the University of Minnesota.