I remember reading about a guy who had a scheduled task run at 5 pm. It would check if he was still logged on, and if he was, it would automatically send an SMS to his wife to explain he would be home a little bit late. It would also check if he had logged in by 8am, and if he hadn't it would automatically send an e-mail to relevant parties saying he was running late.

There's a repository with implementations of those scripts in multiple languages at https://github.com/NARKOZ/hacker-scripts