On a slightly different subject, Reddit, the social news aggregator site has a series of "non ad" ads they run. Usually a picture of a kitten or something to thank the users for not using adblock. One of the admits asked /r/photography to submit some selections for new "non ads." I had three submissions:
The above images are the size (300x224) necessary for the ad space. Click through on any of them to go to the Flickr page for larger sizes, EXIF, etc.