NEW IDEA: Defense Stats...
This has undoubtedly been mentioned before... but...
I'd like a post-battle stats page (i'm thinking about for defense here).
This should show a breakdown of how well your defenses did. Eg...
1) How many troops did your archer towers (or mortars, air defense etc) kill.
2) How many did your clan reinforcements kill.
3) How long were enemy troops engaged with your walls.
4) How many did spring trap take.
5) How many did bombs kill.
This can then act as feedback for people to adjust their base designs.