It is an app that will change your desktop wallpaper, on WindozeXP, for any on Flickr.[HERE]
This shows a wonderful usage of the Flickr API.
It is a great example of why opening up the API of your web application can have wonderful, and sometimes unexpected, side benefits.
I have set mine up to update my desktop with all images tagged with “landscape”.
Some of them are just totally amazing.
If you use windozeXP then this might interest you.