Myself also a student I have to agree with you on the earphones point, and my rucksack is is the most important piece of everyday equipment I could have. It contains all the crap you get given from college work, and of course the important stuff (which I also keep in the infrequently used compartment): Inova X5, smalll size survival tin, Supertool 200, keys (with Photon and data storage device), batteries, Walkman, secondary torch (flashlight for the yanks) with a small knife, wax paper and matches attatched, etc...
I keep some of the other useful stuff in my trousers (pants - is this patronising?): Opinel folding knife, wallet, lighter, parachord, and so on.

-urban bushman