Viewfinder is a simple way to organise photos. You can quickly search for photos based on where or when they were taken. Outside of that, you can also share select groups of photos with friends. Within the sharing ecosystem you can chat about photos, star them to save them to your own library, and keep track of your friends photos easily both online and in the app. It works a bit like iPhoto with its shareable photo streams, but the ability to chat about photos makes it worth checking out if you’re interested in sharing large groups of photos with friends.
Viewfinder (free) [iTunes App Store]