In a Channel 9 conversation, user Dr. Herbie expressed his long-standing desire to see his Outlook calendar as a desktop wallpaper. This, I admit, has never once occured to me. The nice thing about it is that it's so amazingly simple to implement.
A less lazy developer can make this much nicer, with a monthly date-picker and less ugly buttons. Considered as as Proof of Concept, it works with some caveats:
1) Due to the whole Eolas/ActiveX lawsuit fiasco, you need to click on the desktop once to enable interaction with the ActiveX control.
2) You can click on desktop icons, but you can't drag them around (well, without dragging them into an appointment. :). This can be fixed by resizing the control to allow some free desktop space, I suppose.
3) This keeps an instance of Outlook permanently in memory. Probably isn't a problem, but good to know.
4) As it stands, the control will mirror the view current selected in your Outlook calendar.
Here's a screenshot of my desktop right now. Thanks for the idea, Herbie!
Download the specified attachment (CalendarWallpaper.zip) and unzip into any convenient place. My Documents, for instance.
Then, Go to your desktop properties -> Desktop -> Browse and choose the unzipped file (CalendarWallpaper.htm). Et voila!