Opternative - Online eye exams - prescription in 10 minutes!
WebGazer.js - Eye tracking on the browser
Peek Vision - Professional eye exams from your phone
FOVE - An eye tracking virtual reality headset (pre-launch)
Night Eye - Night Eye is a browser extension that enables dark mode on any website you visit. It does not ruin your browsing experience by simply inverting images.
Jabberwocky - Communicate through text to speech by moving your head