I have used photo sites on and off. They are a convenient way to share photos with others. I am more familiar with Photobucket than Flikr, as I have been a member and used it recently. Sites like this are great for sharing photos of family events, especially when you have a large family spread across the country. I am not drawn to the concept of creating a community through this type of site by exploring and commenting on the photos posted by other people.
The Tags feature on Flikr makes it easy to search the site the way you would search for images on Google. Another feature touted by Flikr is the ability to set parameters for the use of your photos by other people. Of course, the assumption is that the person who uploads the photo has rights to it, which might not always be the case. The photo I have uploaded here was taken from Flikr and may be used with attribution, which I diligently offer: cc="http://creativecommons.org/ns#"> CC BY 2.0
I do not see an application for this type of photo site for my students. In our school, we share photos for the yearbook, newsletters, etc. on our server. When the students are looking for photos they are already comfortable using Google to search for them. They learn how to properly use and attribute photos in their tech classes.