Had a 3D designed part that needed some grippy texture to not slide on a textile piece. Instead of using an array of randomly-sized raised dot, I decided to have some fun and generate a DXF of my face from MetalFusion's halftone image converter and extrude the features onto the surface of my part. The dots range from 0.1 to 1 mm in diameter and the part was printed on a Stratasys Objet30.
Cool, except nobody can afford an Objet to recreate this. Maybe that's what makes it unique.