What Should Self Taught Programmers Learn?

BeardedChimp writes: I like many others here have learnt to program by myself, starting at a young age and learning through fiddling. Starting with basic I've learnt c++, java, python, php etc. but what I want to know is what I haven't learnt that is important when taught in a traditional computer science education. I have a degree in physics so I'm not adverse to maths, what books/websites would you recommend?