I'd recommend you to try KanbanTool http://kanbantool.com . This application will help you to gain at-a-glance visibility of your workflow and to efficiently manage tasks (using card colors, priorities, due-dates, file attachments, comments and to-do-lists). KanbanTool provides also useful features that empower team collaboration (advanced account access privileges and sharing options, adding tasks or comments via email as well as email notifications for task assignments and comments).