Back in early 1990s, I volunteered for a year at our local
   Cerebral Palsy center. One of the things I did was learn and
   then fit all of the computers with assistive technologies.
   Special keyboard buttons, straw interfaces (similar to hawking's
   old straw interface), image boards, all kinds of alternative
   devices,depending on the abilities of the users, who were all
   kids under 21.

   I'd learn the device, get it to work (there was no USB, so it
   was a little tricker), teach the teachers, and ALSO teach the
   kids how to use them, until the teachers were proficient enough
   to take over.

   So it was pretty cool. I've been waiting for a decent webcam
   "notice slight movement change" to control computer for a long
   time, and the one he uses is a good one. I'm downloading it now
   to see what it can do. I've always been fascinated by alt-input
   methods, likely because of my experiences... and because I was
   diagnosed with cerebral palsy and was helped by that same center
   up to the age of 5, allowing me to enter school regularly
   without any signs of it.

   So even though they talk about this for ALS sufferers, I see it
   as a great free alternative to the VERY EXPENSIVE stuff they
   have for various disability centers.