The latest iPhone software lets you easily take screenshots of just about anything. To grab one, hold down the Home button and press the Sleep/Wake button. The iPhone will deposit a photo of the current screen in the iPhone's Photo application.

You can force-quit an application by pressing and holding the Home button for 6 seconds.

When you are browsing a website on your iPhone's Safari browser and want to add its icon to your home screen, press the plus sign and select "Add to Home Screen". The image in the icon, however, is a screenshot of the page you were on. So if you want the icon to look a specific way, zoom in on a particular item on the page. Whether you want the website's logo, or some picture on the page, simply zoom in on that part of the page before you press "Add to Home Screen".