From Nikep Software Lab:
Photostand changes the wallpaper of your PC automatically. It can use pictures on your HDD and web pictures on the Internet. Photostand collects many different kinds of Web wallpapers on the Internet Web Wallpaper servers and enables you to set those images at your PC's desktop. Photostand recommends more than 40 thousands pictures from the Wallpaper servers' databases. It changes wallpapers at each interval with a specified displaying style. Users can be choose a interval and a style from the predefined value in the menu. Pictures are selected from the folders list randomly or sequentially. The list can contain any folders on the local computer as well as shared disks. It also support the Internet Web wallpapers. Specifying some keywords for pictures, and the server selects picture's URLs from the database and sends one to the application. Then the application set it as the wallpaper automatically. The details of the service is described in the pages linked from the application page, in which you can find the link to "Internet web wallpaper" and to samples of the picture database stored in the server.