Sally taught me that you can take a picture of your iPhone screen by pushing the Power and Home buttons, briefly, at the same time.
I can think of at least one really useful application for this: When you want to get a copy of your email server details, before you start messing with them for some bad reason.
Where else would you use this?
Jane's Lessons Learned 
Oh – I finally have a comment for your LL! You can take a screen shot within ANY app on your iPhone or iPad… so there are unlimited options for it! The screen shot goes into your Camera Roll.
Thanks Deb! My mom can use this to show me what’s happening on her iPad when I am in phone support mode! Keep the comments coming!!!