Look at PS file (layer) source info

[Tim Sainsbury]

Say I have several layers, each containing a photo. How would I find out more about each photo, like the filename for example? I have created a composite image but now can't remember which photo I used for a particular part and really can't work out how this can be done....

 

[The Magik]

The best way would be to rename every layer as you go. That way, you're always 100% sure of what's in every layer. Time consuming, but the only way. As soon as an image is pasted into PS, it just becomes another layer, it loses its identity in a way.

 

[Paul MR]

There isn't much you can do with the psds you have, but in future IF you have CS4 you could utilize the script here that will keep the information within the layers metadata.
http://www.ps-scripts.com/bb/viewtopic.php?t=3045