Hey,
as in WoW and other MMORPG games I would love to see that user-created addons could be added to the game in order to personalize and expand the gaming experience.
Kind regards
Wolle
Personally, I don't like the 3rd party addons, they can be easily exploited in order to breach someone's account.
What I would love is to be able to customize the UI and to have directly implemented in the UI stuff like damage counters.