I am always using my desktop like my real desk, putting all the current work on it and I clean it at least once a week.
That said in one week it can get pretty messy, so I was looking for something allowing me to split it in categories to keep things tidy.
Fences seems to answer my request quite nicely and I love the double click function to hide or display items...

It uses a bit of RAM (about 40MB for me with 7 fences), so check it out and make sure it is not having a negative performance impact on your system.

http://www.stardock.com/products/fences/