Non-destructive photo editing
Non-destructive photo editing through Aviary would be great so you can always revert back to the original image.
Right now, you either have to keep your originals outside Flickr; or, have duplicates of the same photo in Flickr - the original plus an edited version. I do the latter since Flickr is my primary backup and storage option, which is a little clunky.
Fred Nureddine commented
What now since Aviary is not an available feature any more?!!