The goal of the CMUcam project is to provide simple vision capabilities to small embedded systems in the form of an intelligent sensor. Since the project is open source, everything they've done is available for download and use in your own projects!
This is probably the most impressive use of Lego's Mindstorms robotics kit. The robot does exactly what you're thinking, solves the rubik's cube. Build instructions, software & an awesome video are all available in the write-up.
The MEAN gps project is meant to use inertial movement (sensed by accelerometers & gyros) to predict your exact location if your GPS reception goes dead. The project write-up includes a software overview & hardware schematics.
Another cool application of accelerometers is in this acceleration sensing glove. This project write-up comes from a student at Berkeley tasked with deciphering hand motions/gestures. The software & schematics are all right there waiting for you.
This robot is a direct creation from Cornell University's ECE 476 Microcontroller course. Using a microcontroller it actively seeks out the source of a sound and moves towards it...audio source tracking!
One of the more interesting sensors to be seen recently is the MEMS accelerometer. This tutorial write-up shows an example of how to take data from an ADXL320 2-axis sensor. Give it a look through!
One of the newest technologies to hit the commercial market is the accelerometer sensor. It's in cell phones, the Wiimote and many other consumer products. They're cheap, accurate & have a decent response time. This article goes over what it is, how to use it & how to understand the data using an AVR microcontroller.