The best thing I ever rec'd in college was when my aunt sent me a gift certificate (this was before gift cards were so common) for the local grocery store. I have no idea how she got it since that chain is not even in the part of the country she lives in, but it was a most welcome gift. I would also say WalMart or Target gift cards.
As for little things...I liked spiral notebooks and pens, but your neice might use a notebook computer. Non-perishable snacks (like granola bars, nuts, dried fruit -- I would try to stay on the healthy side) are also good so she has something to munch while studying late at night and doesn't have to cook. Coffee or tea if she drinks it.
My aunts have a little tradition of sending $5 in a card to all the neices and nephews for the "minor" holidays -- like Halloween, Valentine's day, etc. That was always nice to get even though it's a small amount. Now they send the card & $5 to my kids who are also thrilled to get it (my kids are a preschooler and toddler, so they just like anything in the mail).