Create a new image, and use the Type Tool to create some text. If you are using Photoshop 5.0 or later, right click on the T icon on the text layer, and select Render Layer.
Next, holding down Ctrl, click on the text layer to select it's transparency.
Press Q on the keyboard to enter Quick Mask Mode.
Press Ctrl+I to invert the mask.
Now, in the menu go:
Filter > Pixelate > Crystallize...
Crystallize by 10 pixels, and hit OK.
In the menu, select:
Image > Adjust > Brightness/Contrast...
Drag the Contrast slider to 96, and Brightness to -75 and hit OK.
Press Q, on the keyboard, to exit Quick Mask Mode.
In the menu, go:
Edit > Clear