Attention Apple: Steal this Idea

(I don't have the time to write my own right now)

The biggest hugest most absurdly annoying flaw with the iPod / iPhone / iTouch is that there's no way to edit playlists while you're listening to the music -- that being the time that you're listening to it.

You don't always know what song you want until you're listening to music and you want it.

Solution:

Keep the entire iTunes household music catalog on the iPod. Allow me to choose "Add this Song at next Sync" or "Remove this Song at next Sync (or right now)"

Allow the playlists to be editable and to include songs from the catalog even if they aren't currently on the iPod. That way I can build a playlist on the go and push the playlist to my computer.