Unfortunately it doesn't support https-links yet and always shows a random image. But the filters are very nice.
Check out http://lorempixel.com though the variety is a bit limited.
Interesting CC pics from Flickr will certainly save me from adding more cat pictures to the web - http://placekitten.com/
Cute service, but if the name's not a joke, then it's pretty unfortunate :)
Curious how this handles attribution.
Looks like each image is tagged in the corner with a URL that links to the author.