Design a new textbook for a psychology class, science class, etc.
Invent a new telephone.
Design a new suitcase.
Design new clothes for soldier/teacher/cook/student/etc.
Invent a new style for a video game.
Create a short story.
Design a new computer.
Invent a new way to protect computers from viruses.
Create a new type of credit card.
Work on solving a problem of your own choosing - a problem that is related to your major field of study.