Terry Tao's General Exam: "My harmonic analysis was far from satisfactory" (web.math.princeton.edu)

I remember coming across this when I was studying for similar exams in a math PhD program at another university. It helped me realize that I didn't have to know everything in order to pass. (And I didn't! And I passed.)

We also tried to have a web page like this but I didn't bother writing up my exam - after it was over I just didn't want to think about it.