It would be nice to be able to cluster tasks in groups. Especially when you have large projects, being able to cluster tasks would increase the projects clarity – for the workers but also for the projectmanagers.
In the daily work: when tracking your time, groups would help you to faster find the task you need.
In the reports: If you want to, you can see the actual and planned hours for the whole group and if you need more details you can open the group and see each particular task's hours.
This would be very helpful for us as well.