One topic that isn’t currently in the curriculum that I’d really like to add is detecting, handling, reporting, and recovering from errors. This makes up is 10-30% of the code in real applications, but dealing with errors is almost omitted from textbook examples and tutorials for the sake of clarity  (Tanenbaum’s Minix book being a laudable exception).  I have asked elsewhere for someone to write an entire book on the subject; if anyone wants to take a crack at an hour-long lecture, please get in touch.