Shake to Undo
http://heresthethingblog.com
This is by far my favorite iPhone feature. Let’s say you’ve just typed a long sentence and instead of back-spacing the last letter that you mistakenly entered, you delete the entire sentence. If you give your iPhone a quick and gentle shake, it will prompt t a screen to undo/redo typing. In the case of accidentally deleting something, you can resurrect that text. In the case where you have changed your mind and wish to delete everything you have written, you can shake to delete. It is easy and fun! Hold on tight to that phone!