A composite of 2 photographs, one with a polarizer filter turned to its most effective position (the left) and the other with the polarizer at its least effective.
The difference is mainly in the sky, with the more saturated colours making the clouds really pop out. The filter really cuts through that blue haze which so often affects landscape photos. The orange roofs on the houses also show up much better without the glare from the sun.
The equipment I used was as follows-
Camera: Konica Minolta Dynax 5D
Focal Length: 18mm
Shutter Speed: 1/320 (non-polarized), 1/160 (polarized, to compensate for the darkening effect of the camera).
Filter: Hoya 55mm PRO1 Circular PL.
Hope this helps demonstrate how brilliant these filters are and how important they are to anyone interested in landscape photography. It's so difficult to replicate this effect in image manipulation software and at any rate it would take a long time.