Sick of missing people who come to your front door? DIY enthusiast Daniel Garden was, so he built a system that notifies him on his Pebble smartwatch when someone rings his doorbell.
Garden's system uses a Raspberry Pi, a Pebble Smartwatch, Pushover and a few electronics components. When someone rings the doorbell, it triggers the Raspberry Pi, which sends a message through Pushover to the watch.
It's a simple solution that's easy to set up on your own. Head over to Garden's site for the full guide.