Ela S. Great Outlook extension - Taskline integrates your tasks optically and functionally in the Outlook calendar view:
"When you run Taskline, your tasks flow around the appointments in your Outlook calendar. Each task is assigned a start and finish date, automatically taking into account the task's duration and priority, any deadlines, and what hours are available for work. Taskline gives you much of the power of expensive Project Management software, but at a fraction of the cost and with none of the complexity. You also have the convenience and familiarity of using an Outlook-based solution."
