Thanks for your replies.
You can forget my suggestion #3

I have another suggestion :

I receive many photos from my users, and they prefers to send them to me by upload ftp or a CD.

I then have to load them on their behalf.
The problem is that all photos are tagged with me (my pseudo) as people having sent the photos.

My suggestion is to add, in the admin section/photo management a new option (on top of "Remove checked photo and "Change category of photo checkd". This option would be "Change the submiiter of the photos checked", followed by a drop-down box with all users of the site.

I think that this would be great for many users of this great module