I have a flickr account, and I’m currently uploading a few hundred photos from a trip to africa a few months ago. I really like the ‘tags’ paradigm that flickr (and others) use to categorise photos.
However I’m a bit dissatisfied with the tags user interface. Currently you have to select photos and add tags. So if you want to add the same tag to a bunch of photos, you have to select each one (say into the organisr) and then add type in the tag.
What I’d like to see is a page where you are working on a certain tag, and you can add or remove that tag from photos. That should make it easy to see the photos that are tagged with that and make it easy for all your tags to be consistant.