Another way to securely delete the trash in Snow Leopard
Her’s a very simple but potentially useful Snow Leopard tip. As you probably know, you can set up the Finder (in both 10.5 and 10.6) to securely empty the trash by default. You do this in the Finder’s Preferences, on the Advanced tab.
But what if you don’t always want to empty the trash securely? If you want to do it on a one-time basis, you can use the Finder -> Secure Empty Trash menu item. (If you do this a lot, you can make a keyboard shortcut for that item, using the Keyboard Shortcuts tab of the Keyboard System Preferences panel.)
Here’s one other option, especially for those of you who prefer to use the mouse: You can securely empty the trash from the Trash icon in the Dock (this only works in Snow Leopard). Hold down the Command key, and then click-and-hold (or right-click) on the Trash can icon in the Dock. When the Trash’s Contextual Menu appears, it will read Secure Empty Trash (instead of the usual Empty Trash).
Select Secure Empty Trash from the contextual menu, wait a while (a long while if the trash has a ton of stuff in it), and your trash will be securely emptied.