I think, together with ND filers, this is the only type of filter I now use with my digital cameras. It's the only filter that cannot be reproduced in post processing.

The polarizing filter (also known as a Pol filter) can actually do more than darken a blue sky. It can take away reflections from windows or dampen reflections from wet leaves. It also lengthens your shutter speed by up to 2 stops. Those are things ...