Cast bars. You half got it with the Flip Horizontally option. Now just make it so the bar fills/decreases in the opposite direction too, instead of just moving the spell icon. Ability to turn off portraits when not in combat. Ability to seperate the buffs from the frames. Allowing bar buffs instead of icons would be great too. Player skinning of the UI would be great. Allow us to turn off portraits for individual frames. Companions on the Raid frames! Or even better, a seperate element for party companions. I often duo as a healer, and like to keep the party frames small. This makes the party companion frame absolutely tiny. As a dedicated clicker, I'd love some form of click healing, a'la Healbot/Vuhdo. I suspect that's a pipe-dream though.

Yes, because wanting to be able to get rid of the ginormous Unit Frames and their artwork, for a more minimalist UI design makes me a baddie.