I love the idea of giving them something for a new apartment (if they're moving out) since it's such an exciting time. If they're going to college, I had a friend get me a really nice quality school sweatshirt that I still have today (and I graduated a hot second ago). It's also a really sentimental time, so maybe a photo album? I love Artifact Uprising for those.
If they are planning on living away from home, I was thinking a gift card to Target or Walmart. I'm sure there is something they will need for their new space.