My sister filled an airtight container with all kinds of meds - pain relievers, cough syrup, first-aid cream, itch cream, band aids, tums, pepto, thermometer, anything you might normally use at home, 'cause at one time or another, they'll need something.
Storage containers, small laundry hampers, towel sets, shampoo, razors, or single-serve meals, microwaveable soups, pastas, anything that will keep without refrigeration. Snacks like Rice Krispie treats, individually wrapped cookies, chips, etc.
A storage rack for cd's,dvds, drawer organizer and school supplies. Also some kind of hanging organizer that hangs from the closet rod. The girls use small dry-erase boards outside their doorm rooms for messages, not sure if the boys do that too.
Sending my 2nd DD off in a 2-year span, so I'm pretty practiced at this point!