Projects developed, by MIT students and former students, both in the classroom and independently are proving the worth of cellphones as useful devices, beyond the obvious, and particularly in developing nations. Software developed as entries to MIT's IDEAS or $100K business competitions, or as part of the MIT Media Lab's NextLab program are being used to help residents of underdeveloped countries to increase their incomes, learn to read, navigate to where they're going and diagnose their ailments. The fact that cellphones are small, relatively cheap in comparison to computers, and increasingly more powerful and connected, makes them ideal for these countries that have little in the way of infrastructure. The MIT News provides details of some of the projects here.
