I'm using two excellent apps at the moment. KanbanFlow helps me keep track of tasks and I can share what I need with my team. It has a great interface and we now tend to think of our whole lives as a series of Kanban projects! Newly discovered and quite awesome is Workflowy. It has taken me a few weeks to really understand the power of it but I love it and use it to keep all my "to do" lists organised. You can share but at the moment I keep this to myself and use it for brain-dumping, brain-storming, planning etc.