As filament9 has said, materials are native to ZBrush. Every 3D app has its own
types of materials -- known as Shaders in some -- and they aren't compatible with one
another. Some programs use reflection maps, specularity maps and other such things. Other
programs don't. So it would be very hard to ever make materials directly exportable -- and
even if it was accomplished they would have to be done through a dialog box that lets you
pick the particular program that you plan to use the material in.
However, there are ways that ZBrush allows you to transfer colors that are generated by your
material onto the texture. For one thing, Projection Master allows you to "Pick Shaded",
which transfers all visible color to the texture regardless of whether it's arrived at by
painting or through materials.
Also, Projection Master will let you pick up materials as a part of the texture. This is
awesome while you are working within ZBrush, but the material channel won't export with the
texture for use in other programs. However, you can unwrap the texture onto the canvas and
then use the MRGBZGrabber with Shaded RGB turned on to capture the material-generated color
as a standard texture.
A bump map can easily be generated by clicking the Texture:Make Alpha button and then saving
the resulting Alpha from that palette. For things like reflection maps, you can easily paint
them yourself by unwrapping the texutre, creating a new layer, and then using pure white
paint the reflective areas in. A moderately low RGB Intensity in the Draw palette will let
you have considerable control over how much reflection you want. More white means more
reflectivity. When you have your map painted over the texture, turn off the texture layer --
resulting in a pure, black and white map. Now you can use the MRGBZGrabber (with Auto Crop
OFF) to pick up your reflection map for use by any program that will use it.