A while ago Eric Holscher blogged about things he didn't learn in college. I'm going to take a different spin on it, looking at both things that I did learn in school that I wouldn't have learned else where (henceforth defined as my job, or open source programming), as well as thinks I learned else where instead of at college.
Things I learned in college:
Big O notation, and algorithm analysis. This is the biggest one, I've had little cause to consider this in my open source or professional work, stuff is either fast or slow and that's usually enough. Learning rigorous algorithm analysis doesn't come up all the time, but every once in a while it pops up, and it's handy.
Finite automaton and push down automaton. I actually did lexing and parsing before I ever started looking at these in class (see my blog posts from a year ago) using PLY, however, this semester I've actually been learning about the implementation of these things (although sadly for class projects we've been using Lex/Yacc).
Things I learned in the real world:
Compilers. I've learned everything I know about compilers from reading my papers from my own interest and hanging around communities like Unladen Swallow and PyPy (and even contributing a little).
Scalability. Interesting this is a concept related to algorithm analysis/big O, however this is something I've really learned from talking about this stuff with guys like Mike Malone and Joe Stump.
APIs, Documentation. These are the core of software development (in my opinion), and I've definitely learned these skills in the open source world. You don't know what a good API or documentation is until it's been used by someone you've never met and it just works for them, and they can understand it perfectly. One of the few required, advanced courses at my school is titled, "Software Design and Documentation" and I'm deathly afraid it's going to waste my time with stuff like UML, instead of focusing on how to write APIs that people want to use and documentation that people want to read.
So these are my short lists. I've tried to highlight items that cross the boundaries between what people traditionally expect are topics for school and topics for the real world. I'd be curious to hear what other people's experience with topics like these are.