For the Trippy or the Hippie
Everything that was old is new again.

Everybody who was alive in the 70's remembers the infamous lava lamp.  These things are back and are super color coordinated.  These are great for college kids and teenagers of all sorts.  Furniture and appliances are rare in college kids households and dorm rooms.  Most highschool kids have so much free time (especially in the summer) that you can rest assured many hours will be spent just staring at a lava lamp.

If you know the color of the gift receiver's room or their favorite color, just choose something corresponding.  If you don't then buy it from some place like SPENCERS where it can easily be returned and is only as far away as the local mall.

Just try to keep yourself from buying one for your own place.