Jean Pierre Charalambos just released a new version of his excellent Processing library, Proscene 0.9. Proscene provides classes to ease the creation of interactive 3D scenes. This new version incorporate many new features, among them a third person camera.
Clicking on the following image takes you to an online applet generated with one of Proscene’s examples, Flock. You can move around the flock of boids by using the mouse. Pressing the space bar cycles through the arcball, walkthrough, and third person modes. Clicking one of the boids and switching into the third person mode will make the camera follow the selected boid. Download the library package from here.