Some desktop interfaces come in sections with a mini-map to show you where you are within the wider desktop area, like Mac OS X's Spaces feature. People don't necessarily understand this or get on board, but now our web browsers are all tabbed, which suggests a different approach. Imagine being able to create new desktop tabs in Windows for different purposes. It certainly sounds like a winner to me. Some programs exist to do this already, but they are in early stages in my estimation.
And without adding too much complexity, we could easily have our desktops zoom in and out, effectively encompassing as large a virtual area as necessary while still allowing close-up or overall views. The mouse wheel is perfect for this.
Mokalus of Borg
PS - It seems such a clean and obvious design to me.
PPS - I wonder if anyone is working on something like it.