I have one of those little vapor fountains on my office desk. The module is called an ultrasonic atomizer (http://www.siansonic.com/UltrasonicAtomizer.htm). They are easy to find on line for pretty cheap. Many have LEDs in them too.
The one I have produces fog that lasts for about 8-10 inches distance. The fog will sit in place for a good 30 seconds, but if it's moving around, it dissipates pretty quickly. The atomizer creates a spout of water and quite a bit of splash, so you'd need to protect the circuits from that. They must remain submerged to keep them cool and some have a protection sensor that shuts them off if the water is too shallow above the element.