Another trick is to listen to your favorite songs at a very low volume -- loud enough so you can still hear them, but quiet enough so that you can't quite make out the lyrics or the melody. After a while of this kind of listening, your mind will fill in the gaps in a creative way.

This is great for getting inspiration for music making, as what you hear will have a strong resemblance to what you already like, but will be different in subtle and interesting ways.