A navigation bar is provided for switching between modules within an expanded communication service such as email, calendar, contacts, tasks, etc. and for providing preview peeks associated with each module to a user. A temporary preview of a module may be provided upon a hover action over predefined navigation bar locations such as icons and/or textual identifiers without actually needing to switch to a module. One or more preview panes may be docked or pinned to a dynamically selected or user defined location on the main user interface so that they are permanently displayed within the main user interface. Users may be enabled to undock one or more of the docked preview panes through a user interface control. New or interesting activity within each module may be highlighted by displaying an information badge next to a module name, for example.
