Pranav Mistry, Pattie Maes and Liyan Chang, researchers from MIT's Media Lab, created an invisible mouse using an infrared laser beam on the right side of a laptop keyboard and an infrared camera on the right side of a laptop screen. Their prototype cost them all of $20. Chances are the invisible mouse will cost you even less.
Some people literally see beyond the limitations of others to invent and develop assistive innovations that open doors to disabled persons. In this case, Dr. Dennis Hong, from Virginia Polytechnical Institute and State University (Virginia Tech), made some in'roads' for blind persons with his invention of the world's first blind driver vehicle.