We all know the iTunes system for rating songs: five stars are for the greatest hits of all times that you’ll never stop listening to, while one star goes to those horrible songs that inexplicably got listed in the iTunes library. Between these two opposite poles, there are three more intermediate ratings to describe your music collection.
However, there are other ways to use this rating system. Some people, for example, use it to mark low quality songs that may need some optimization work done on them. So, while listening to music on the iPod, if you come across a damaged track you can give it a one-star rating to fix it later on.
Another interesting alternative usage is rating songs according to their mood, so for example, romantic songs would get one star and dance songs would get five, with three more stages in between to create three extra mood categories. Then, by using the iTunes Smart playlist tool and this rating system you could easily create custom playlists according to your mood in a given moment.