YOU guys are right on. Tupperware and plastic baggies!
I will put maybe 1 (if any) book into my bookbag, hit up that caf, and load the bag up. Sometimes I used to make 10+ trips. I would snake everything from hardboiled eggs (great), to veggies, to lunchmeat, to chicken breasts.
As far as class goes, I usually make a few sandwiches and throw them in baggies, and eat on the fly.
The best thing about college food is you can load up on it, all you can eat, except it may not always be the healthiest.
In my 4 years being at college I became quite adept at loading up on food.
In fact, the past 2 years (jr and sr year) I get the '1 meal a day" plan, and will steal so much food I barely have to buy anything at the grocery store.
Does wonders when you can snake a whole dozen hardboiled eggs and 6 tuna sandwiches!