Attention and eye movements are thought to be a window to the human mind, and have been extensively studied across Neuroscience, Psychology and HCI. However, progress in this area has been severely limited as the underlying methodology relies on specialized hardware that is expensive (upto $30,000) and hard to scale. In this talk, I will present our recent work from Google, which shows that ML applied to smartphone selfie cameras can enable accurate gaze estimation, comparable to state-of-the-art hardware based devices, at 1/100th the cost and without any additional hardware. Via extensive experiments, we show that our smartphone gaze tech can successfully replicate key findings from prior hardware-based eye movement research in Neuroscience and Psychology, across a variety of tasks including traditional oculomotor tasks, saliency analyses on natural images and reading comprehension. We also show that smartphone gaze could enable applications in improved health/wellness, for example, as a potential digital biomarker for detecting mental fatigue. These results show that smartphone-based attention has the potential to unlock advances by scaling eye movement research, and enabling new applications for improved health, wellness and accessibility, such as gaze-based interaction for patients with ALS/stroke that cannot otherwise interact with devices.