The June issue of NASA Tech Briefs describes an inchworm-like MEMS device that produces linear motion in precise increments measured in naometers over a range of a few hundred microns. The actuator was developed by E H Yang and uses a combination of piezoelectric drive and electrostatic clamping. There are a lot of potential uses for such a tiny actuator including tiny microsurgical robotics and other precise positioning systems. For technical details and diagrams see the full tech brief (PDF format, free reg. required).