One convenient addition could also be a big search box at the top that gives me access to "archives", so that I can still listen to the older songs even when they go out of the top 40 list.
I love the UI!
I especially like how the video plays in the header while rest of the page selection remains the same. This way, I can go back and play my #2 choice after my #1 choice has finished without having to look for it, I already know where the #2 choice is.
Youtube is horrible at this. If you don't make a playlist, you have to click back and hope it still recommends the same videos as the last time you were on that page.
