Allow tagging, etc. in when typing in the New Item box
One thing I really liked about my previous GTD app (Doit.im) was the great ability to add characteristics to new items while entering them, using only very simple keystrokes.
A new item might be entered as "Fix faucet @Home #Bathroom remodel ^Next". So the area, the context and the project can be set (if you choose) very quickly without mouse clicks or tabbing through different fields.