1) Gift Cards
Who doesn't like gift cards from Starbucks to the person your buying favorite's store its the easiest way to give to someone who maybe you don't know what in particular what their favorite piece of clothing or accessory is.
2) That one book that everyone is talking about
Being in high school there is always that one book that everyone is talking about right now it's "The Fault in Our Stars" that seems like everyone has read but if the person you're buying for hasn't read it buy it for them so they can join in the fandom.
3) Netflix Subscription
All I have to say is who doesn't love being able to have all seasons of Gossip Girl accessible to them?
4) Electronic Gift Cards
If you're extremely last minute I mean like Christmas Eve late a lot of stores offer electronic gift cards which are a life saver to the procrastinator shopper.
My personal favorite but everyone cannot live without their headphones especially for runs, exercise or school (my personal use). They are absolutely a lifesaver.