One thing I would love to see is the template editor have the option to modify the white backgrounds in the forums. My old forum layouts were very dark and switching to this was a bit of a shock to my board mainly due to all the white (they love it besides that).
Just an idea, not sure how easy it would be to implement.
You will see a new option in the admin settings where you can switch between "Light" and "Dark" modes. It allows you to darken white elements but still use the current colour styles. Looks pretty good actually.
Will update you when its ready.