From a technical standpoint, the idea of basing a design on interactions with webcams is quite fascinating. You could even try and do facial recognition through

From a technical standpoint, the idea of basing a design on interactions with webcams is quite fascinating. You could even try and do facial recognition through that and see how far away somebody is from the monitor to adjust text-size for instance. But it's hard to see that idea taking off for general usage. The second somebody visits your website and sees "This website is requesting permission to access your webcam" they're going to be a bit freaked out about that and might be hesitant to interact with that site further.