Open Safari. Say: 'Make this application speakable'. Then say: 'Define keyboard command'. A window will open, and you hit the keyboard combination for a shortcut, let's say Command-left arrow. Write the command: 'Back'. Save. Now you can not only say the default window commands like: Move page up, move page down, move page to top, move page to bottom, but also 'back', and you will see Safari go back to the last page you visited. Now, say 'Define keyboard command' again, and this time hit command-right arrow and write: 'Next, please' (this works for me, forward doesn't). Now you can go back and forth in Safari with your voice.
The urls in the menu bar each have a command+1, command+2 and so on for nine favorite places you often go to. Now make these places speakable! Whoa! Mac rules! Safari rules! And, of course: Command-Alt-P: 'back to basics' (the new Safari command to go back to the mother site). Instead of 'back to basics' you can also say: 'back to the mother ship. It's your choice! And Command-Alt-S: 'back to search' (the new Safari command to go back to the search results you started with). And Command-Alt-B: 'Navigate' (my choice) will bring the bookmarks on/off. Nifty!
[Editor's note: You can, of course, use Speakable Items with other applications ... but people often overlook this feature, so I thought it was worth a mention, and the Safari context seemed timely...]

