Ever want to implement a technology but never had the opportunity? I have. Piezoelectric actuators are my white whale. We're talking: > sub-nanometer resolution > µs response time > 100 billion cycles w/o failure > extremely high stiffness > force generation up to 80 kN > low power requirements > no mess Yeah, there are definitely limitations, especially regarding displacement (the largest of stack actuators typically max out at 300 µm / .012" travel) and control (upwards of 1000V required + $$$), but for the right application, they are indispensable. I've seen plenty of precision piezo-driven X-Y stages in person & been mighty impressed. The dynamics are so high that they almost don't look real (similar to the way a jumping spider moves). They also tend to sing while operating. The part that really interests me from a large machine design standpoint, though, is the extreme response & control combined with high force. For example, if you need to tilt the head of machine or move a table rapidly & accurately (ahem, CNC gear shaper I'm looking at you), these might be a good alternative to a mechanical cam driven or hydraulic design. I'll continue to keep these filed away for another day...