Ask HN: Using eye-trackers with computers/smartphones?

1) I've always thought that it would be useful if you could design content to be responsive to what the user is looking at (you'd have to be careful not to overdo it, but I think it has the potential to add a lot of value). 2) The eye tracking data could be used to make recommendation engines more effective. 3) The eye tracking data could be used to make website analytics more effective. Privacy: I think people might be reluctant to use it at first because of privacy concerns. However, I think the value it would add would lead to its adoption over time. Plus, you'd have control over it (could turn it on and off depending on the site for example). Question: Is anyone working on integrating eye-trackers with computers and/or smartphones?