An alarm clock with a separate speaker forcing you to get out of bed to turn it off!
I made a Magic 8 Ball to make all my important decisions for me by attaching MPU 9DOF and OLED C clicks to a BeagleBoard.org PocketBeagle.
Chicago hackerspace Pumping Station: One uses BeagleBone Black and RFID to control door access
Lower the barriers of entry to VLC research
Audio Video Streaming
Pegasus Touch SLA Printer
Golang RFID authentication for ps1auth
Burning Man project with a 23-foot tall pyramid with more than half a kilometer of LED strips
It ain't going to play itself... oh wait, it is.