Better than Flick
I'd read about Flick some time ago, and decided to try it out. I gave up soon after, as it doesn't allow you to compare the current photo with the others taken at the same occasion. When I googled for that ability, Alpaca showed up, and it's almost perfect. It has minor inconveniences, like separating photos that clearly belong together, but it sure looks promising. The interface is much prettier and more refined than that of Flick, by the way. Cheers.