University and conference registration systems have been done to death as homework and textbook examples. Ditto for payroll, flight booking, online stores, video rentals. Try to think of some area of interest you have ... sports, hobbies, etc. Can you imagine organizing events, recommending equipment, anything like that?
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi