Tired of realizing at 4 am that I was supposed to go to bed at midnight, I took my raspberry pi from it box and finally gave it a good use. I made a small app that allows you to send reminders to the raspberry headphone from your main computer. So you can do something like this from your terminal:
remind go to sleep 3600
That will create an mp3 with the message "go to sleep!" and play it over the speakers on your raspberry pi after a delay of 3600 seconds (an hour).
Code can be found here, feel free to modify it at will.