Smoke and Fire? Just saw this the other day for Blender 2.5, haven't done it myself though so I can't say how easy it is. http://cg.tutsplus.com/tutorials/blender/introduction-to-smoke-simulation-in-blender-2-5-day-1/ http://cg.tutsplus.com/tutorials/blender/introduction-to-smoke-simulation-in-blender-2-5-day-2/…