I wiggled my finger as fast as I could, and the servo reacted immediately. Bend sensors would be perfect for small robot antennas to feel obstacles or to feed back a gripper's position. Use them in a location where a switch just won't work. The bend sensors might also be good as a bumper switches. A VR glove would also be fun for a teleoperated robot.
Bend sensors are cheap enough to use in all kinds of projects.
This company specializes in lots of cool stuff for robot experimenters, such as voice recognition boards, digital and analog compasses, tilt switches, and more. Be sure to ask for their catalog.