As you know I'm working on a new GNOME Shell theme called Switch. I'm working on some new details for the theme which will make it look more consistent with the new found CSS features.
Take a look at this Screenshot of Switch. Not only does it try to look consistent with the menu even though there are some limitations, the player buttons glow like the hover text on the menu in the theme preview. Also you'll notice that the panel icons have a nice inset effect like the text and on press the icons glow like the text as well.