In addition to what has been said above, I would suggest carrying a small amount of cash, maybe $20 or $30 or so that you never use, unless it's an emergency. While things can always get REALLY bad, I would imagine that in most situations like those you mentioned, you might be kept from your dorm for a day or so, and there would be a lot of other students in the same boat. I think it would be nice to grab a bite at a fast food joint, or knock a beer back with a few friends. I know a lot of students who have almost all their food money on a school account so they can buy meals at the school's cafeterias, but if something happens, those might not be availible. Just my $0.02.

I would also second Nishnabotna's comment about backing up school work and such on a flash drive. Could really save your bacon.