ShowTime/2

ShowTime/2 is a simple utility that adds a bit of pizzazz to your desktop by rotating your choice of bitmaps as backgrounds. Along the same vein and as an extra little tidbit it will also do slideshows.
 * Rotate background bitmaps
 * Cycle through bitmaps in order or Random
 * Run slide shows
 * Multi-threaded
 * Save prepared shows
 * Large multi-selection fileboxes
 * Normal, tiled & scaled mode
 * Change background colors
 * Startup with backgrounds
 * Easy setup
 * Set priority

It is part of Pillarsoft Suite.