I've finished a mod that lets me track the image ids each user has downloaded. It's works like the lightbox feature in that it stores a list of image ids in the 4images_users table. The mod also stores the date of the most recent download and lets you query users from the admin CP using a date range.
If anyone is interested, I'll post the mod in the next few days in the published mods forum.
If anyone has more questions about this mod, post them here.
