The Dock gives you quick access to your applications from anywhere on your Mac. It's the fastest and most convenient way of opening any application.
Using keyboard shortcuts is the best way for beginners to become more efficient Mac users. Close? Open? Minimize? There is a shortcut for that.
Mac OS X has a great built-it search function called Spotlight that helps you find any file on your Mac. Never loose an email or a document again!
Guest logins is a convenient and secure way of letting friends (or strangers) use your Mac without letting them access your personal files.