Outlook On the Desktop is a free application that will place the Microsoft Outlook Calendaring system right on your desktop, so that it’s visible and useable all the time without actually having to open Outlook.
The Outlook Calendar is pinned to your desktop so that no windows can get stuck behind it, the Calendar´s position, size and opacity are all adjustable via a very intuitive GUI.

Free Download: Outlook on the Desktop 1.3.3 (429 KB)

Requirements:
Microsoft Outlook 2000 or higher
Microsoft .NET Framework 1.1

Link & Image: Droll Things