It would be nice if there was a custom field with ranking functionality so you didn't just have to use a drop down with numbers. For example, you'd be able to set the number of places available in the ranking (e.g. 1-20). Then if the task in the 1st ranking gets completed or removed, all subsequent items would move up in position. Or if one task gets added with a 5 ranking, it would back all items 5-20 back one position