Right-clicking
Macs doesn't have right click buttons, something that often confuses new “switchers”. Instead, it has the right-click which work similarly.
Address book
The Adress Book app on your Mac is a great and convenient way of keeping track of phone numbers, email addresses and other information.
The Dock
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.
Keynote
We love Keynote — Apple's own presentation software. The application makes it possible to create incredible presentations with very little effort.