I wonder too if it would be a good thing to change "d" so that it floats the item down to the bottom of the current file? That way done detritus piles up fullfillingly at the bottom of the page, leaving current events at the top.
Might be sufficient to just override "Sort lines (F5)" to sort DONE to the bottom? That would be another benefit of sticking the current date into the front of done items.
cheers (getting things done already :-) ) t