For me, it's shared photostream.
As a teacher, it never fails to amaze me how I am finding new ways to integrate my Apple devices into my teaching.
Recently, my colleagues had just returned from an excursion to the zoo with their pupils, and now had cameras laden with photos that their pupils would go on to use in their powerpoint presentations (project work). Bearing in mind that these are 7-8 year old children, and the laptops they use in the classroom (we have 1-to-1 computing) have no network drives). We can't use flickr or Google+ because they are considered social websites and prohibited in our school. Some teachers in previous years had taken to passing around thumb drives, which was both cumbersome and time-consuming.
I had the teachers consolidate the photos and pass them to me. Copied them to iPhoto on my macbook, uploaded them to photostream as a public website, and shared the link with them. They posted the link on their class blogs, and the pupils could just visit the blog, click on the link, and download the photos they want. It was practically *****-proof, and really made the whole process of disseminating pictures seamless.
For me, it's shared photostream.
