Make a motion activated wreath with Arduino and MP3 player. via instructables
This wreath uses an Arduino microcontroller with the Adafruit MP3 shield and a Parallax PIR motion sensor to detect if someone is approaching the doorway. It then plays a custom greeting pre-recorded and pitched to sound like an Elf, after which it plays a random Christmas Song. The song(s) will keep playing as long as the PIR sensor picks up motion within 15 seconds.