Idea: On the main page, where all my games are listed, it would be great to add a (sortable) column 'my remaining time' to the list of games 'Opponent's turn', where my opponent has to move.
Even though I'm not due to move on those (my opponent is), I think it is useful to see how much time I have in each game once he does move.
For example, if the lowest number showing is greater than one day, I know I do not have to use vacation for at least one day, even if my opponent moves right when I log out.

I understand that the feature is not the greatest since sliced bread, but it would probably be quite easy to implement.