Well I was impressed by drempels a few weeks ago but this blows that one out of the water. The effects in this are simply stunning. Mouse cursor Particle Effects, animated desktop image (with lighting effects and possibility of reacting to music playing in Winamp). I won't ruin it for you by listing it all and besides I am still playing with it. Just pop along and check it out.
The image is with lighting effect and the light follows the mouse. Reflecting on the swimming pool rippling in the background. (And at a decent rate while I'm running all the apps at the bottom.
This is on a P3 500 256MB 3DFX Voodoo 3 3000. Uses 3D card for effects.