yes, you can use a polarizer for many situations. you can reduce/eliminate reflections from glass and non-metal surfaces, and increase saturation as well.
depending on what you're shooting, you can make a difference with BW film.
to maximize polarization, your light source has to be at a 90 deg angle to the camera. if you point at your subject, and raise your thumb (like you;re shooting a gun), that's where the sun should be for maximum polarization.
to eliminate the reflection off a glass surface, for example a store window, shoot it at a 30 degree angle.
sean