http://cg.tutsplus.com/tutorials/autodesk-3ds-max/create-a-cool-smoking-text-effect-using-fluid-mapping-with-particle-flow/

In this tutorial, you will model, light and texture some simple 3D text inside of 3dsmax. Then, using Particle Flow, the built-in particle system, along with the FumeFX plugin, you will simulate some convincing looking smoke to add a visual interest to your otherwise run of the mill 3D text .