My idea is a very simple one - it would be cool if you could re-order the buttons on the home screen. If that is not clear, I am talking about the ones that say "Matchmaking" and "Public Games" and "Store".

In the HoN 2.0 patch, the Settings button was removed from the row, and I really liked that button being there, since it made options a lot easier to change on the fly. In the same vein, I never use the Player Ladder button, so it just sits there taking up space. I think it would be really cool if you could rearrange these buttons to your own liking in a sort of drag-and-drop style, making the UI nicer to use for each individual user.