One thing that has always annoyed massively is that all my ratings get lost when I reinstall my system. And that happens often.
I know from MediaMonkey for Windows that it is possible to write the rating to tags. Interestingly, when loading the songs into Banshee, for instance, the ratings are recognized in fact!
But apparently, Banshee does not write ratings to the ID3 tag itself. Which player is capable of that?