A frequent complaint from PC users about the Mac is the single button mouse. The paragraph below explains the reasons a single button mouse can be advantageous, and its origins:
The one button mouse has the distinct advantage of not having hidden functions that are only available through right clicking. And for those who are mentally challenged at figuring out right from left, or those who are more inclined to use the mouse with the left hand than the right, the single button mouse makes perfect sense. No brain twisting happens with the single button mouse. Jeff Raskin who was one of the founders of the Mac platform decided on the single button mouse for these reasons. At least multi button mouse support exists in the operating system now and you can plug in almost any USB mouse to a Mac. So the one mouse button complaint is practically specious.
In addition, Apple does have contextual menus, but they are available through the control key + mouse click, and in Mac OS X 10.3 through the Action toolbar buttons on windows that look like gear wheels.
Apple's Mighty Mouse and its wireless version also available at the Apple Store and authorized retailers now gives you the ability to have multiple button mouse using Apple hardware and its supported software versions. It ships also with new Mac Pros and iMacs. Mac Minis you can add your own.
Macbook and Macbook Pros offer on the trackpad a "Place two fingers on trackpad and click button for secondary click" option in Apple menu -> System Preferences -> Keyboard and Mouse -> Trackpad.