After looking at lots of different PHP gallery software I decided to use Coppermine.
I'm really like it but just wanted to offer up an idea which might improve it.
The idea is to have smart albums which are automatically generated based on the meta data of images rather than be assigned to an album.
For example this would allow me to add the word "kids" to the exif comment field of images I upload and I would then be able to have a smart album which would automatically fish out all of those images.
As well as specifying how images are found to be included in each album you could also specify how they are grouped. So for eaxmple you could say group by rating and you would get the album kids with the sub albums, 1 star, 2 star, 3 star, etc. Or you could specify that they should be grouped by date, for example, Year/Month which would then give you this kind of structure:
Kids
Kids/2003
Kids/2003/January
Kids/2003/Fenruary
etc..
The code used to build up these groupings or search criteria could be well defined allowing people to write their own mods for grouping and collecting images.
Any thoughts?