Winwall is a free utility that enables you to manage and set your archived images as wallpaper with ease.
Key Features:
Support for BMP, GIF, JPG and PNG images
Add single files or whole directories
Search for images on hard drive
Download wallpaper from the internet
Change wallpaper:
at startup
at random time interval
at any given time interval (secs, mins, hours)
Choose pictures randomly or consecutively
Apply visual effects on wallpaper
Play sound on change
Custimize display mode and alignment of wallpaper
and much more | 
