Basic Auto Attack so I can save my poor finger the pain and aches of spamming Melee Attack.
having a new talent/ability "retaliate" what allows you counter attack automaticaly the enemy which attacked you first would be nice (and useful).
other option (or addon) could be "berserk" where you auto attack everything you see. could be fun parking your char in the middle of chicken's fence and got beserk and watch.
Shift+Click or Double Click to move items to the sell window of a vendor instead of click and drop.
as said above, last game update came with shift/ctrl + click options. check the release notes.