For several years now, About.com Cats has featured a Cat Picture of the Week, and this year is no exception. Photos are chosen from submittals to any of the *other* Show and Tell picture galleries on this site (most often from the galleries listed in the Cat Monthly Picture Calendar Guide). All the Show and Tell picture galleries include an online form, where you can fill in the form and upload up to two pictures of your cat.
My criteria for selecting Cat Pictures of the Week include the quality of the photo, and the care in presenting the "story" behind the cat. I am less inclined to select submittals where I had to do heavy editing.