Since Safari 4, the Add Bookmark button (+) is now attached to the left hand side of the address bar. If you choose “Customize Toolbar...” from the View menu you can remove just about every item from the Toolbar, but unfortunately it doesn’t seem possible to remove the Add Bookmark button without also removing the address bar and the Google search box. However, this is a way to get around this.

First, open up the Customize Toolbar dialog box and find the Add Bookmark button in the top row that is separate from the address bar. If you drag this to the toolbar, the button that is attached to the address bar will disappear. You are now free to drag off the separate button that you just added. The one that’s attached to the address bar won’t reappear, leaving you with a nice clean toolbar.