Opinions amongst DV's amateur photographers on the use of protective filters in front of camera lenses? I'm not really interested in any of the artistic applications of filters (coloured lenses, polarized lenses, etc.) at the moment, although they can certainly be discussed.

I'm a bit of a purist, so I'd hate to put any unnecessary glass between the subject and the sensor. Then again I'm quite paranoid about nicks and damaging the lens coatings... surely the lens hood and my usual careful handling alone would do a good enough job of protecting the lens, but... Also the good clear filters are quite expensive, so it's not just an issue of image quality loss.

Thoughts?