I'd love it if more UIs were as customizable as in games. Specifically MMOs/WoW. I haven't played in a good many years, but one thing I loved in that game was customizing the pulp out of the UI.
Most of the modifications you can do to your WoW UI is done through addons. With user-scripts/extensions you could probably modify your Google UI as much as you'd like.
I assume that's asking a bit much, though.