I've been thinking about this a LOT lately.
There are a number of GUI additions and a few back-end updates I'd love to see also. For instance, I made a rather long post and I kept having to scroll aaaaaaaall the way up and back down anytime I wanted to add a new image to my post. The editing tools should be locked in place at the top of the screen and scroll with the user. I like these types of posts, they're good for the advancement of the steemit platform.