Tobii bundles some (Windows only) integration software with their EyeX. It allows you to click on whatever you are looking at with the press of an action butto

Tobii bundles some (Windows only) integration software with their EyeX. It allows you to click on whatever you are looking at with the press of an action button (left ctrl key for me), along with a few other features (eye tracking the alt-tab switcher is what I really like). It works okay, but eye tracking isn't quite as accurate as a mouse and you either need to make your icons big and widely spaced or you have to zoom in (with an action click) before selecting the icon precisely.