[hnthrow098767]

I haven't graduated out of university yet.

I would appreciate anything that's challenging and helps me improve my programming skills.

[high_na_euv]

Go for compilers then

It will significantly improve your understanding of programming langs, how some of them suck, what is possible, etc, etc.

[tiberious726]

It's not a course, but I definitely recommend the book "Deep C Secrets", I couldn't put it down, and had a similar feeling to being in a good, difficult, class.