How do I make the hard drive visible in the Finder?

1. While in the Finder, go to the "Finder" menu and select "Preferences".
2. From the "General" tab, place a check next to "Hard disks" -- this will make your hard drive visible on the Desktop.
3. From the "Sidebar" tab under "Devices" again place a check next to "Hard disks" -- this will put your hard drive in the sidebar of any finder window, and should also add it to "Open", "Save", and "Save As..." dialog sheets (as well as others)

If you are an administrator on the computer you should have no trouble adding files and folders to the root directory (/)

This was troubling me for a while on my wife's computer. I had everything checked in preferences and it still wasn't showing up.

Then I found that if you rollover Devices on the sidebar in the Finder window, there's a little Show and Hide that pops up.