1. You can move the "dock" icons.This trick is overlooked, and you should know that the four icons located on the bar at the bottom of iPhone are movable: Phone, Mail, iPod, Safari. You can move them by pressing and holding the icons, and drag them while shaking. After all movements done, you should press the home button, and here you are: new design of your dock. There can be put any 4 icons on that dock, so if you need anything from the main menu icons, you can drag them there. Note the difference between these two iPhone screens!
2. When browsing the Internet, you can double tap any column, picture or even word to fit your screen to its width. This is very useful when reading blogs, or browsing column-designed web pages. Check out the image, and see how we fit the screen to the middle column size.
3. iPhone's headphones have also a multifunction button. The native headphones have a button on the microphone, and, when in a call it can be pressed once to answer a call, press twice to send the call to voicemail, and again press once to hang up. If a second call is coming while in a call, you can click once to hold current call and then switch to the new call, or you can hold for 2 seconds and then release to ignore the call and keep the current one. When you are out of call, you can press once to activate iPod and play songs, and the same one click can pause and release the song, and pressing twice will skip to the next song. These are some easy to remember tips about the button on the headphones, and it think they ease a lot your experience with the iPhone.
4. I think it happened at least once to any of us: backing up and syncing the iPhone, and when the hour long back up is almost done, but you receive a call. The whole back up or sync process is void, and you have to start it all over again. To avoid this situation, you can start the sync/backup process and then pull out the SIM card. This doesn't damage your phone at all. Put it back when the process is completed, and this way, the backup won't be interrupted. If, on the other hand, you want to end the backup or syncing, pull out the SIM and then pop it back.
5. For a fast soft reset, press and hold the Home button and Sleep one to restart the iPhone. A light will flash, the screen will shut down and then back on. Keep holding the buttons until the screen turns back on, and here it is: you made a soft reset of your iPhone!