If you do NOT use the network time option (which I always do, since it means never having to set the clock), you can use a unique method for setting the time under OS X.
Open the date and time prefs panel, and use the mouse to drag the hours and minutes hands where you want them ... this will set the clock! Pretty cool, and potentially useful if your machine is not connected to the internet on a regular basis.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010313014635163