I used to use other LEGO elements to separate tightly bound pieces in my collection. My thumb nail and I were quite pleased when I first discovered an actual brick separator LEGO introduced to ease the task. How many styles of LEGO element separators has LEGO made available to the general public?
Bricklink lists two:
OLD (in two colors):
NEW (in three colors):
There is one other 'separator', but it doesn't look like it's very good for bricks: RC Car Separator Tool - Metal
ETA: The Clickits Separator!
As of 2020 there is another brick separator designed for removing more tiles with a single motion and included with the Mosaic sets.