The developer of Natural Scene Designer has released Terrain Texture Shader, a freeware Mac application for enhancing shaded relief. The software, based on an algorithm developed by Leland Brown, renders DEMs as georeferenced images with increased contrast and detail.
A practical use of texture shading is for mapmakers to merge it with shaded relief. The two techniques when combined can improve many terrains, clearly depicting drainages and revealing small details. Depicting rock textures in alpine mountains is another use for the software that shows promise.
I posted a tutorial about Terrain Texture Shader that includes a link to the download the software and an image gallery.