Four things I really wish I had learned in school, but did not because it was not on the curriculum and I did not hit it in the course of my projects

1) Source control

2) A web framework. Any one would have done, just to have some experience with MVC before I was 25 would have been really nice.

3) SQL

4) We actually studied project management, and even had a semester with an actual project doing it, but my present self wishes my past self had done it more. (Exposure to a non-waterfall methodology would have been a bonus.)

If these aren't in your curriculum, get exposure by yourselves. Your future self will thank you for it.

(P.S. You'll learn a lot of things over the next four years which you'll never use again. Pay attention in Data Structures, Discrete Math, and absolutely any time you hear the word "caching". Operating systems, compiler design, hardware design for non-hardware developers, and whatnot are more like brain candy for engineers.)

Edited to add:

Things I most benefited from my university education.

1) My ArtSci degree. It involves a human language (Japanese). I highly recommend picking up one of these for every engineer. It will make you think better (really), it will make you code better (I have been in charge of internationalization on every job I have ever had, starting with internships, because I "get" it), and it cannot possibly hurt your employment prospects.

2) AI class. Less because I learned AI, more because it introduced me to scripting languages (awk in my case), which are just indispensable.

3) Java. Hey, if you go to a Java school, you might as well graduate being pretty good in it.

4) I paid attention every time I heard the word "caching". And yay though I walk through the valley of the shadow of traffic spikes, I shall fear no performance degradation, for caching is at my side.