I came across the eyewriter website today while surfing for processing and interactive concepts at 2010.futureeverything.org and thought that the technology, use and application was quite inspiring really given the DIY approach to technology and what these guys have managed to put together.
It must be so frustrating for anyone suffering from ALS and communicating.
Members of Free Art and Technology (FAT), OpenFrameworks, the Graffiti Research Lab, and The Ebeling Group communities have teamed-up with a legendary LA graffiti writer, publisher and activist, named TEMPTONE. Tempt1 was diagnosed with ALS in 2003, a disease which has left him almost completely physically paralyzed… except for his eyes. This international team is working together to create a low-cost, open source eye-tracking system that will allow ALS patients to draw using just their eyes. The long-term goal is to create a professional/social network of software developers, hardware hackers, urban projection artists and ALS patients from around the world who are using local materials and open source research to creatively connect and make eye art.
http://eyewriter.org
Here is the Video from the Open Frameworks site which is what Eye Writer is based on and uses.
I am no C++ developer myself and would always opt for processing.org for this stuff.