In some situations, attempting to intimidate the other person will actually increase the amount of rapport you gain with them. CEO introductions, meeting other salespeople (and competitors), and sales job interviews come to mind.
Other times its just plain fun to assert a little power in a situation.
Here's the technique for giving a "power handshake" that communicates that you are confident, in control, and not afraid to use it.
The key is getting your grip first into the area past where the four knuckles join the fingers to the hand. Once your hand is in here, the other person will be unable to squeeze anywhere near as hard as you can. This establishes your dominance in the situation.
Use this technique carefully. Using this technique on people who are easily intimidated, will only make gaining rapport even more difficult. However in some situations it will actually increase your rapport.