Support for classical music.

iTunes treats individual movements as "songs", not part of a complete piece of music. So, you can't, say, click on Dvorak's Piano Trio in F minor, you have to first create a temporary album to hold all three movements.

Also, the searching is messed up for classical music. The composer's name, for example, is sometimes under "artist", and sometimes in another column, and sometimes not there at all. A column for "composer" would fix that.

Those and a few other obvious and easy tune-ups would make iTunes usable for classical music.