The smoke machine has been an invaluable diagnostic tool for the last ten years. It is used to find leaks in systems that handle air such as evap systems and induction systems. It is a smoke generator that delivers an ultraviolet smoke at low pressures of about 1 psi. The following pictures were taken of a CIS system undergoing a smoke test:

In the above picture we can see coming from the seam of the left corner of the airbox. An additional leak is coming from the screw head at the inside corner of the box.
In this picture we can see a leak around the rubber sleeve for #3 cylinder. The hose clamp was tightened yet it still leaked.
We can see here that there is a leak at the injector seal (o-ring). The standard prtocol is to replace the bakelite insert and inner and outer o-rings.
And lastly, in the above picture we are seeing a leak from the toilet seat seal even though we have added a weight to simulate the force of engine vacuum holding the lid down.

So in summary the smoke generator is an extremely valuable tool with respect to diagnosing 'false air' in induction systems and leaks in evap systems.