By default, OS X puts all of your mounted items on your desktop. That means that whenever you plug in an iPod, open a .dmg file, or put in a CD you get more clutter on your desktop. That drives me bonkers. Here is the quick way to get rid of all of that nonsense:
1) Go to the Finder.
2) Hit Cmd+, to bring up the preferences.
3) Go to the “General” tab in the menu.
4) Now uncheck all three boxes under “Show these items on the desktop.”
Now your desktop will remain free of useless clutter. All of these will still appear in the sidebar of your finder, so no worries. Just head there if you need to get at your mounted items.