This is so simple it probably doesn't count as a hint, especially now that we've got Expose, FUS and apps that create multiple desktops. But I'm currently working away from home on an old iBook (OS 10.2.8) without much memory, so simple is handy. I use my desktop to collect and organize current files, folders, images etc. so it gets pretty cluttered. Add to that the desktop background images I use, and the visual stimulation can get a bit confusing.
So when I want to "remove" the clutter to focus on a task that may require a few of the apps, folders, images etc., I fill the screen with an empty Sticky, which functions as a clean backdrop. Using either the dock or a launcher I can then cause just what I need to appear in front of the screen. I can also use the Stickies note backdrop as a place to store text, URLs and images temporarily. And when I'm done, a double-click on the top bar of the note (or Cmd. M) rolls the Stickie up like a window blind.
It's not perfect by any means: e.g. one click on the backdrop means it gains the focus and I lose sight of things I was working with. But it's easy, and, as I said, simple -- which is sometimes good.
[robg adds: Another similar solution is the freeware Backdrop...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2004060616051549