I'd use the rating systems to
- Remove songs that I may become tired of listening to but don't want to "Broken Heart" it in order to remove from my Samsung Focus. So let's say I discover a great new song and 5 star, then go to 4 star it, then I'm kinda tired of it so i'd make it three stars. I could review 3 star songs on device or playlist and remove them if i want.
- Reverse of that I could easily make a favorites playlist by Genre or Artist by only including 4-5 star songs.
- Use 4-5 stars songs to put on my Gym Zune (8GB zune) by only selecting Rock and Fitness songs with more stars and it would make it easy to drag and drop onto device when i sort by Genres or Artist.
To play Devil's advocate, I'd say that you're not really using the ratings as ratings in those systems. You're using them to organise music.
Perhaps there is a better way to achieve this rather than putting a ratings system in place that is not going to be used strictly for its intended purpose. For example, if Zune gave you access to all the tags in your music files you could use a tag for 'category' or similar and use that as you currently want to use the ratings.
Of course fixing the ratings system would allow users to rate their music in more detail and allow users such as yourself to use the ratings in more creative ways as well.