I’m promoting the idea of open content libraries this year much. Thus, I put up a wiki to try and collect other sites that are already accomplishing similar tasks like Open Clip Art Library and Open Font Library. It is called Open Content Library.
Right now this site is a wiki so that anyone can add their site. The idea though is that this could develop into a way to search many different sites’ open content.
For now, if you know of any general media/content categories, please add them to this wiki page so that we can get a better picture of what is out there. I’m specifically interested in what exists in the video and 3d model space, as I haven’t looked into it much.
NOTE: The Open Font Library logo competition is growing quickly. We hit 40 total submissions so far, this weekend. Please submit and join in the fun 
At the moment the openclipart site seeems to be down for quitte some time