Did you even know that in the file info window in #iTunes you can use Ctrl+V to paste album art from the clipboard or from the filesystem? Did you know that you can have multiple pieces of art for a file?? @gnome #RhythmBox and @kde #Elisa can't even edit album art.
You can pseudo-trim songs in iTunes by setting custom start and end times; it doesn't alter the file, but start/end will be skipped when played, as well as on iPod. Per-file volume and equalizer adjustments? Separate per-file strings just for sorting Title / Artist / Album?
Also #podcast and audiobooks are managed with all the same above features. Did you know that Microsoft added podcasts to #Zune Player, but not Windows Media Player?
Each playlist can have its own columns and ordering. Album art can be inlined and scaled within.
Look at this, Linux developers. Linux has *nothing* to compete with this.