How do i get ride of unused and unkown things on an ipod?, How do i get ride of unused and unkown things on an ipod?

My ipod use to be used for all kind of things from games, photos, and music. now I want it strictly for music and I have cleared almost everything off of my ipod. when it is connected to my iTunes there is a section on the storage bar that says "other" I don't know what that other stuff is and all I know is its taking up space that I could use for music. any ideas how to figure out what that stuff is or how to delete it?