Viewfinder (free, with some in-app purchase options) is a bit like the Photo app in iOS, but on steroids. With your permission, It takes your image library and arranges it by time and location. All photos remain private and only you can see them unless you choose to share them. Nothing is uploaded to the cloud, although the app requires a free account. Photos you share with others can be shared by them to others, so keep that in mind before you use the sharing options.
You can import contacts from your phone, from Gmail, and Facebook. Once contacts have been imported, Viewfinder shows you which friends have also set up an account on Viewfinder. In-line messaging and commenting are supported for creating communities
