Time Entry and due dates
We run payroll for clients, some of them are weekly. So we have weekly tasks setup, we also have subtasks setup. We have an "invoicing" subtask which might not get cleared for a few months. Meanwhile the payroll processing tasks stack up since the subtasks haven't been completed. When our payroll person tries to enter her time the tasks are all the same, so there will be 10 payroll tasks that are identical that she can enter her time to. If there were due dates associated with the task that were easily seen in the time entry screen it would be helpful.
You should also be able to enter your time to a task after it has been completed. Stuff happens and maybe the task wasn't actually complete, having to create a new task or "uncomplete" a task just to enter time isn't a great solution.