(click image to enlarge)
In this design idea, the default view is one of arbitrary length (likely from 3 - 7 days) with today always being placed on the left hand side of the screen. Each panel (groups, the calendar, and tasks) can be dragged and dropped in any order. In the group section, the user can expand or contract their groups on an individual basis. When contracted, it shows only the group name and the + button for expansion. When expanded, it shows the group name, a link to email all members of the group, a link to schedule something for all members of the group, and an secondary tree that can expand to show all the names of the members of the group. Clicking on an individual's name will show you their complete schedule, while clicking the schedule link will overlay (with gradients) an aggregate of all members' calendars on top of your own. Additionally, clicking anywhere on the group button itself, will cause all associated events on your calendar to be highlighted (i.e. the other events will fade slightly). Clicking additional groups will also highlight them, and clicking again will turn off this highlighting. Groups are also drag and droppable within the group section, allowing the user to put them in any order they choose.
Scheduling in the calendar for yourself or others is the same as Outlook and Planzo. Click and drag to create events, drag and drop to move events, or double click to edit event info. When you click on an event tied to a certain group, that group will be highlighted on the group list, causing the others to fade slightly. Also, when another user attempts to schedule you for an event, that event appears on your calendar with an icon indicating that it has been scheduled by someone else. A notice at the top of the screen appears asking if you wish to attend the meeting. If you accept it, it will be integrated into your calendar like your other events.
Lastly, tasks are managed similar to groups. You can expand or contract tasks as well, allowing you to either view task notes, what group the task is tied to, and the due date, or to only show the task name. Tasks are also drag and droppable within the tasks section. Users can choose to have tasks sorted by group or by due date as a default. Finished tasks fade slightly and are placed at the bottom of the list. They will disappear after a certain amount of time automatically (or unless the user wants to clear them immediately).
Though colors are completely optional, all tasks, events, and groups that are linked can be rendered in the same user-chosen color.
(click images to enlarge)