Abstract: Flexible and extensible combination user interfaces are described. Combination user interfaces combine task-based and deductive user interfaces in such a manner that complex user interactions can be facilitated using a more meaningful and intuitive user interface than would have been possible using task-based or deductive user interfaces exclusively. The described combination user interfaces are flexible and extensible. They are flexible in that users can work on multiple tasks or switch between tasks without first needing to complete another task. They are extensible in that they can be extended to add, modify, or remove tasks or portions of tasks. User interfaces can be extended by manipulating metadata associated with the user interfaces. The combination user interface can be combined with an Inbox concept to facilitate saving and assigning tasks. The Inbox represents a work queue for a user.