BioniX Wallpaper is a wallpaper manager that can change them one by another at time intervals the user can specify.
You just have to choose the images that will be rotating and to adjust other options regarding the wallpaper reproduction, such as a visualization at random or respecting a created list.
BioniX Wallpaper is fully free of charge and it is expected that the following versions come with a system to share image files (BMP, GIF, PNG, JPEG/JPG, EMF/WMF) included.
Among other features, it is worth mentioning that the aspect of the program can be personalized through Winamp skins; it does not require any installation, thus it does not add any file to your system (DLL, ActiveX, updates, registry entries, etc.) and uses 2MB bearing in mind that they come with some sample wallpapers.