Here’s a handy tool for anyone who needs to keep track of a large number of roommates or family members. Take a Bluetooth USB dongle, a monitor, and a Raspberry Pi, and you’ve got yourself an automated way to see who’s at home or in the office at a glance.
This project requires that everyone have Bluetooth activated on their smartphones, so the Raspberry Pi can identify which devices are present. Any time someone is in range of home, the display shows that they’re present (or at least that their smartphone is). Check out Instructables for a step-by-step breakdown.