mkdir realDesktop
mv ~/Desktop/* realDesktop
And then delete the original Desktop:
rm -r Desktop
Finally, create a symbolic link to your new Desktop folder, called realDesktop:
ln -s realDesktop Desktop
This allows you to use your Desktop as normal from within applications, while maintaining a perfectly uncluttered view. Works well for me.
[robg adds: I believe, but have not tested the theory, that the result of this hint is that you can no longer drop something onto your desktop, thus keeping it clean. Caution: If you're going to try this, make sure you have a good backup of the items on your desktop before you begin, just in case you mess up the Terminal backup or something else goes wrong. Second, although there shouldn't be any negative repercussions of this change, you can never tell what might happen down the road. Personally, I just leave the desktop as-is, though the only things on it are a few folders and any 'hot' items that need attention...]

