As mentioned before, APNGs are still hard to find and we need to create more of them ourselves. So I tried something. All three of them are based on Creative Commons or Public Domain content (for sources follow the links under the thumbnails) and therefore free to use, of course. Just click on the thumbnails on the right to watch them in full size.
sidenote: WordPress prevents me (probably by accident) from embedding animated PNGs directly in the article. To be more specific: If I do so, they are shown as a still image, but not as an animation. The reason is that the width and height of the image are automatically added as an attribute right behind the file url, for example “animation.png?w=500”.
This way, Firefox doesn’t seem to be able to interpret the PNG as an APNG and the animation is gone. And I can’t do anything to avoid that. So I chose the ugly way and embed them only as thumbnails, so the animation will appear when the images are opened in full size. Better than nothing.
Or does somebody know a workaround?
edit [2015/01/05]: Almost forgot to name the image sources.