$15 for this one-trick pony? Whatever.
Here's a tip for free:
If you absolutely need to drop files on the desktop, try creating a few folders and label them by category.
Place each of these folders in the dock. Right-click to set the view options as you like.
When you're dragging a file to drop on the desktop, from Safari, for example, flick it to the "show desktop" screen corner to activate expose (set expose options in system preferences) and reveal the entire desktop. Drop the file in the appropriate folder.
Now for the groovy part: you can access each of the file groups right from the dock! Just click its folder to see all the files in a category. If you want you can add custom icons to the folders so it's easy to tell them apart in the dock.
Now for the far out, mind blowing part: drag your desktop folder (in your home directory) into the dock, and you can click on it to access everything on the desktop. Set the stack view options to view content as list, and you can drill down to all the category folder contents as well! Mac OS X even gives the desktop folder its own special icon.
The cool part about this method is that the dock folders are always in full view, their contents one click away. With view options set to view them as stacks, you can see at a glance whether they're empty or contain items. No need to activate expose so you can see a bunch of labels on your desktop. And since your files are already in category-specific folders, you're one step ahead in getting organized. The category-specific folders will also hold and manage a lot more files than the desktop alone, which quickly degenerates into an impenetrable mess regardless of how many $15 labels you make.