Examples:
Decorative LED based light that changes colour.
Games.
Dice.
Communications via - Light, Infra red.
Small robots, line followers, Light seekers, maze solvers (wall followers),
Infrared control of somehing (curtains, a robot)
Emergency beacons for accidents, car breakdown etc.
Home security.- Alarms or detecting security lights.
Dimming or night operating lights for home or garden.
Bearing in mind that at GCSE (16 years old) can only deal with low voltage systems, although they would be able to use a commercial mains power supply.
or
you really should choose your own project - Can your teacher advise you as He/she will know you a lot better than us.
Projects we have covered in the past few years include:
Light seeking robots
Robot kits as toys
<A href='http://www.xs4all.nl/~sbolt/edz.htm' Target=_Blank>External Web Link</a>
Dizzy an aware robot.
Automatic cat flaps
Security lights with sonar
Speed trap for radio controlled cars
Bike speedo
Robot arm
Rev counter for a moped (erratic operation)
Mood lights
Automatic lights - Dawn/Dusk
garden lights
Walking robots
light chasers for discos
LED jewellery
Strobe light
IR control
Automata
rolling ball mazes
Bike indicators
Fluid level indicators
Industrial plant models including tank empty/fill, conveyors to sort package by size/weighing systems/Monitoring systems for various materials/level monitoring by contact and non contact/flow monitoring, Data logging.
Daylight monitor
Remote control vehicles - IR control and radio using Picaxe to give some intelligent activity.