Photoshop layer photo information relating to location on hard drives.

Hi there.
I've been using Photoshop for a long time.
Something that i think  would be useful would be the opportunity to
have info on the original name and location of a photo once it has been placed into
a layer.
I have a psd with many layers and I now need to know where the originals were imported
from in my file system but have no idea. I run many hard drives and take what I need
from these drives but it would be so handy if I could get a summary for each new photo
I place into a layer information as to where it came from across the many drives that I store
photos. Some of my final images may have 20 or 30 photos comped in.
Thanks.
David Bignell