GIF IT UP was an open competition to find the most excellent GIFs reusing openly licensed images and video from the collections searchable on the sites of the two digital libraries.
I think there is real potential for teaching about open licensing, copyright while having some fun and learning a bit about image editing through the creative use of openly licensed media.
Monsters Are Real – Biodiversity Heritage Library a nice collection of open licence images. The Biodiversity Heritage Library works collaboratively to make biodiversity literature openly available to the world as part of a global biodiversity community.
Lots more of this sort of thing at the OpenContentToolkitprovide a gateway to contemporary and historical open digital media content from media archives and collections around the world. It is a space to explore, discuss and share examples of the use of open media at all school stages and at all levels of education.
Not a open resource but Lego Friends made me laugh and makes a point.