Tool for users to plan their day
Let user zoom in the gantt chart down to 15 minute, 1/2 hr, or hour increment.
Then come up with a planning screen where you can plan out your day by dragging and dropping and stretching tasks in your zoomed in gantt chart.
Allow the user to divide cut up the task over multiple days (since you might want to work on a task for 1 hr per day for 5 days but don't want to see the task stretched over 5 days) if they want to and they can plan out each day with the gantt chart.
Then allow estimated time to be assigned to each task. Add in a dash of time tracking like (Jira issue time tracker) and this would be a killer app.