Something that I think would be a nice UI improvement would be to keep the currently playing track in a fixed position on the "now playing" list, and scroll the list up rather than have the currently playing track move down the list until it's the last item in the view.
I did a little testing, and keeping about 15% of the list size above the currently playing track seemed to be a nice value for this, giving a good balance between displaying upcoming tracks, and previously played tracks.
So if the list is tall enough to display 10 tracks at once, the currently playing track would always be #3 on the list until there are no more tracks to scroll through, at which point it does start moving down the list towards the end. (rather than continuing to scroll up and leaving a blank area)
If you stick to 15%, with 20 tracks it would be fixed at #4 on the list. When displaying 30 tracks it would be #6, with 40 tracks it's #7 etc.
Adjusting dynamically based on the list size seemed to work better than simply deciding that the currently playing track is always #5 on the list, for example.
That number might be fine when you have a lot of tracks being displayed, but not when there's only a few.