Dexter Industries are currently developing a great new sensor, a proper 6 Degree of Freedom (DOF) Inertial Measurement Unit (IMU) for the NXT. It consists of two sensors on a single board; a 3-D gyroscope and a 3-D accelerometer. Both sensors can measure their respective values on the X, Y and Z axes.
The sensor, like many of the other Dexter Industries products before it, comes with a very bright U-R-Blind LED™ to indicate when it’s powered on. This light is also useful when trying to find your way out of a dark cave.
I’m currently working on a driver for it which will be part of the Driver Suite, of course.