“In these 3 video tutorials you will understand how to use strokes and alphas inside ZBrush to create several things like horns, zipper etc. These tutorials created by the Pixologic (makers of ZBrush) for the 3D community, so everyone can easily go at advanced level in ZBrush and extract the full potential of the ZBrush. As always you can also download the files in flv format for later viewing.”
http://www.cgarena.com/freestuff/tutorials/zbrush/pixozbrush/strokes_alphas.html