This would be a non-trivial amount of work, so it's probably low priority, but one nice feature could be to add a calendar to the Progress tab, so that users can set schedules and goals for themselves.  For example, I'm trying to finish the book by my birthday, so I set up a calendar in my study with goals for each day (avg. 20/day, more on weekends, less on weekdays I have other obligations).

When someone has a schedule and regiment laid out, it's much easier to stick to it.