ThingLink is another Web 2.0 tool that allows users to upload or use a provided list of photos, to the site. Once on the site, the original user can "edit" the photo and add tags to it. The tags that you attach can be link to other websites and/or add comments. You may attach numerous tags to the photo. Once you create the photo, you have the option for the ThingLink photo to be unlisted or open for the public to tag and edit.
I used ThingLink to share details about an event we had in school. I was able to tag the photo of the event, with a video, a link that corresponded to the topic of the photo, and a comment describing the photo. Another idea that I have is to post a picture and encourage parents to tag the photo with their related comments, photos, videos, and/or website links. For older students, teachers could post a picture of a topic they were going to study. Students could then tag the photo with information that they know about that topic. It would allow the teacher to evaluate what prior knowledge the class has on a topic.