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Send bulk email to address book group. It's dead easy to create email groups in your Mac Address Book application, and just as easy to send a bulk email to that group. In your address book app, simply click the + (plus) sign in the bottom left of the window, title the group and drag contacts from the main database into the new group. When creating a new email in your Mac Mail app, click the address icon in the menu bar, then simply drag the group name into the address pane in the message. Your application will send the email to all addresses in that group.
Shortcut to your iPhone camera. Now and again you'll see something you need to shoot quickly. Rather than going from your lock screen to your home screen to your camera app, simply press the home button on your phone twice, click the camera icon and shoot. Tada.
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Change your computer's password. Believe it or not, you could someday forget your computer's administrator password. To change your password, boot up the computer from your original system disk, or a retail Leopard or Snow Leopard disk by holding down the C key as the computer starts up. Choose a language and click the arrow to continue. From the Utilities menu, choose password reset then input a password that you will remember. Unfortunately your keychain access utility, which stores the rest of your account's passwords, such as mail, skype, wifi etc, will be deleted, but at least you'll be able to administer your computer and perform software updates.