I like a relatively neat Desktop. I keep out just those items I need to access right away for my day-to-day work. It's so easy to clutter Finder, especially when you use multiple hard drives and partitions, an iPod, a memory card reader and the odd CD or DVD. An often-overlooked Finder preference can come to the rescue.
To hide volumes on your Desktop, choose Finder -> Preferences (or just type Command-, when Finder is active). In the General tab, choose which items you want to show on your Desktop. Place a check next items you want to see or clear the checkboxes to hide items. You can always bring hidden items back by updating your preferences later.
And don't forget: whether you hide disks or CDs on your desktop, they're always there on the side drawer of your Finder windows where you'll find all hard drives, servers, removable media and so forth.