Blink-rate is currently used for drowsy detection in cars (along with several other variables). The in-car cameras are fairly low resolution, comparable to a webcam (e.g., I think Bosch uses a 1MP camera).
In addition to dry-eye prevention, I would love to have a notification that, after detecting a low blink-rate, asks how alert I feel and based upon my response, suggests that I do one of a number of alertness-promoting activities: a game of ping pong, a cup of coffee, or running a new idea by a colleague. After my activity, having returned to my computer, I might be prompted to enter both my chosen activity and my post-activity self-reported alertness level - this could easily be consolidated into a single-click.
Over time, such a system could make better suggestions, moving them to the top of the suggestion-list in the notification. For example, coffee might be found to work best just after lunch but ping pong could be better in the late afternoon.
*Of course, vigilance or working memory tests could be substituted for self-report.