http://www.theatrefx.com/store/comme...t=tiny_foggers
There you go I suppose. If you want to spend over 1200. The others I found are the ones I'm already familiar with.. and good luck fitting one in a case. 6x7x12 (inches) is what Best Buy calls a "Mini Fog Machine".
I suppose if you have a front intake fan and a speed controller you could place the fog machine so it blows the smoke at the front of your case. If the rpms on the fan or low enough you should be able to suck it in without disipating it. I have a broken generic 80 mm fan that spins so slow you can poke a pencil in and out without hitting a blade if your quick enough).
However... I still think its a bad idea. They require a liquid or what they call "fog juice" to create the smoke. Condensation and pc internals isn't something I'd like to play around with.
Besides... if you have 4 cases running in the machine it would swirl the fog so quickly I doubt you'd get the desired effect.