A feature I've long wanted to see in a photo management tool is ranking based on pairwise comparisons. Say you went on a trip and had 200 "keeper" photos, but that's still too many to publish in an online album, and many of them are near-duplicates anyway. If the photo manager let you compare any set of photos two at a time, you could (with n-choose-2 keypresses) find something close to a total order of the set. Then…
It's an interesting idea to let users pick bests out of near duplicates (and maybe prompt the user to workthrough this UI flow on album creation). I've put it on my to-do list!