Applications of Polarisation

Photographic Filters
When light reflects off water it becomes polarised. Such light is often called glare and can make it harder to see what's behind it. Photographers often use filters to cut out glare and get better pictures.
Liquid Crystal (LCD) Displays
There are some crystals that become aligned when an electric field is put across them. When this happens they act as polarising filters.

3 D films
When you watch a 3D film you are actually watching two films shot with different cameras, looking at the same thing but from slightly different angles.
When the films are projected the light is polarised and polaroid filters, worn as glasses, can let just one of the films into each eye.
Stress Analysis
When light passes through some materials its plane of polarisation is rotated. The thicker the material the more it is rotated and different colours are rotated by different amounts. To investigate the stresses in an engineering part you could make a model of it in plastic, pass light through and then put it under stress. The patterns produced which may give an indication of where the material has been deformed.