[vitamen]

It's just CC, not "open source," but there are plenty of places (i.e. Flickr) where you can share your assets for others to use. I've had people contact me about using some of my photos in books they're publishing (wasn't necessary, given the CC license, but gave me a warm fuzzy and was appreciated), and I've contacted photographers about using their work for a wedding invitation I was making. But many of the kinds of things that are actually useful have the kind of specific requirements that make them not fun to create and share for free, so Shutterstock makes lots of money.

[ochoseis]

In that realm, one example I've seen pop up a lot where some kind of video needs to be shown off is "Big Buck Bunny" [1], a project to build an open movie using blender.

[1] https://peach.blender.org