The Rainbow Maker allows you to create rainbows in your own home. All you need to do is place the device in a window that receives direct sunlight, and a solar panel will power a motor that turns a real Swarovski Crystal. The rotating crystal will split the light into a spectrum (a.k.a. a rainbow) that will be visible to the human eye.
Shine the rainbow on a bowl of Lucky Charms for instant comedy gold.
You can pick up a Rainbow Maker from Gizoo for £18.95 ($38).