DeskLickr is a fantastically well named app that epitomizes all that is right with Mac development. Simply it downloads a photo from Flickr and sets it as your Mac's desktop. You can tell DeskLickr to limit itself to a certain Flickrstream, tag, or group.
DeskLickr will randomly select Desktop images for you, and if you don't like it you can tell the app to never use that image again. DeskLickr can be set to automatically select images, or you can manually get a new image. DeskLickr displays a windows, which you can close, with a link to the photo on Flickr and tells you who took the picture (as seen to the left).
[via Laughing Squid]