Here are a few tricks that I use all the time:

1) When you've scrolled way down on the page in Safari or Instagram, you can instantly pop up back to the top by touching the very top of the interface. A huge time saver!

2) It's such a pain to type in numbers sometimes. You have to hit the 123 button, touch the number, and then touch the ABC button to start typing letters again. If you only have to write one number, hold down the 123 button and then slide your finger to the number you want. Let go, and the number appears and you're back in ABC/typing mode!

3) Use a double space and the iPhone will automatically drop a period there for you!

4) I used to hate typing out acronyms cuz I'd have to keep hitting the shift button. But if you double-tap shift, it becomes caps lock! Awesome...

5) If you want your phone to stop ringing, hit the button at the top (the "sleep/wake" button). If you want to send the call straight to voicemail, hit the button twice!

6) If you want to access your most recent apps, double click your Home button. You can scroll through recent apps... it's a great way to see what damage the kids might've done when they get ahold of my phone!

7) If you double click your home button and swipe to the left, you can lock or unlock your phone's orientation with a single click.

8. If you're in a app that's hanging and you want to crash out, hold down the sleep/wake button until the slider appears to shut down the iPhone. But instead of choosing an option, hold down the Home button for a few seconds... the app will crash out! Can save you a reboot of the phone, if you're lazy like me.

9. AutoCorrect is always screwing up the names in my family! "Olive" kept becoming "I love"... so I finally added it as a shortcut under the Keyboard option in my Settings app. Phew, problem solved!
http://gigaom.com/2011/10/14/ios-5-how-to-add-words-to-the-auto-correct-dictionary/

10 Bee taught this to me this weekend and it's my favorite trick. If you're taking a picture with the Camera app, you can use the top volume control to take the picture! It has made my pictures much less shaky, since I can hold the phone with two hands rather than have to use one finger to touch the camera icon on the touchscreen!!

Do you use any of these tips and tricks? Have any others to share?