Normally, we will use keystrokes Cmd-Shift-3 or Cmd-Shift-4 to take snapshot with Mac default screencapture utility. And new in Snow Leopard, we will end up having a PNG image file automatically stored inside our Desktop folder with the name Screen shot … .
Those behaviors mentioned above are the default ones. We can easily change those with simple command lines.
Anytime you are trying to capture a screensaver, you will fail miserably as the screen saver will automatically go off when you try to press any key.
But, there is an easy way to take a snap of screen saver.
We all know that by using Shift Command 3 we can take the capture the whole screen and using Shift Command 4 we can select the region to be screen captured.
There is a hidden trick behind screen capture, if you're pressing Shift Command 4+Spacebar, you will be able to capture a window hovered by your mouse along with the shadow.
You can also capture your menu bar, Dock and even additional menu extras of your Mac. I think you should try it. It's fun.
There are times when you want to take screenshot of webpages, but obviously you can't use simple print screen which can only take part of the webpage as big as your screen display. So what should you do to capture the whole webpage?
Recently, I've found this nice Safari plugin called Saft, which is a Shareware. Saft gives you ability to have a screenshot of entire webpage and save it as a PDF file with a single click.

Feel it. Grab it. Love it.
You can find Grab inside Macintosh HD → Applications → Utilities → Grab. And then follow these steps :