Fuchsia, a graphic tablet is different type of input device (like your mouse), but instead of moving your mouse around a mouse pad, clicking and dragging to simulate drawing (or erasing) you use a stylus (which is shaped like a pen) which feels more natural in developing artwork. The main reason I use a tablet with photoshop is for the control.

If you want more information check out the Wacom website.

For a real trip look at the "Cintiq". With this tablet you apply the pen directly to the screen.

My stylus has not replaced my mouse altogether, but the buttons are alot less worn! ;)