I posted some thoughts on this topic some time ago here.
Here are some functionality that I thought such systems should provide. These are still at very high level and are evolving.
A digital photo album should provide following functionality:
• Add photos from
o Camera
o Phone
o Scanners
o Files, including e-mails
o Web sites
• Opinions
o Tags
o Annotations
o Comments (or blogging about photos)
• Finding photos
o Based on dates, places, people
 Combinations and variations of these
o Content
 Type of picture
 People
 Objects
 Concepts (peace, ambition, love, …)
 Similarity to other pictures
o Based on opinions
 Tags
 Popularity
 Interestingness
• Creating albums
o Events
o Topics
o Evolution of a theme
o Some social aspects
• Sharing photos
o Sending photos
o Monitoring availability
 From friends
 On topics
 Of specific types
• Managing photos
o Using groups to decide access levels for photos
 Private, groups, public
o Editing
o Deleting
o Reorganizing
We can build the detail functionality in all these aspects by looking at current systems and taking the best features from there.
Am I missing some obvious features?
One additional feature that I can think of is import/export (especially the latter). I want my online photo album provider to give me the ability to easily switch to another photo album provider, taking my photos, tags, comments, and everything else with me.
In the future, I hope to see more support for latitude and longitude. EXIF supports it, but I think there’s a great deal of intertia and paradigm paralysis in this area. As GPS technologies decrease in cost and size, hopefully GPS support and geotagging will become a standard feature of digital cameras. I believe the ability to cluster images spatially will be very useful.