By shaking your iPhone you can perform a number of great tasks.

You can turn the 'Shake to Shuffle' feature on or off by going to Settings -> iPod and then setting 'Shake to Shuffle' to ON. It's ON by default.

If you are listening to your iPod music on your iPhone you can simply shake your iPhone to shuffle and immediately change songs. Shake anytime to change to another song.

If you have just typed in a message and decided that you wish to delete it, just shake your iPhone. A pop-up message will appear asking if you would like to Undo Typing, or Cancel.

If you have Paste a piece of text or an image and want to undo it then just shake your iPhone. A pop-up message will appear asking if you would like to Undo Paste, or Cancel.