CameraCalib is a project mainly written in Python, it's free.
Camera calibration tool
CameraCalib is a simple tool that gives focal length (in pixel) and distorsion paramaters from a movie file that captured a chessboard.
This tool uses OpenCV and Qt, and is written in Python (2.7 for now). It's basically made to learn openCV calibration process, but became a tool that I use...
Documentation soon.