I've been wanting something like that for a long time. Eye tracking + a simple keyboard shortcut to trigger a click so I can select anything across the entire system instantly without having to take my hands off the keyboard. So far though I haven't been able to find any decent out-of-the-box solutions for that without any major drawbacks.

Eye-tracking is an underrated user input method in my opinion. I'm hoping eventually VR/AR will make it mainstream.