I’ve discussed forgiveness here a few times (Five Questions with Forgiveness Expert, Dr. Everett Worthington; Anger at God; The Value of Forgiveness) so it shouldn’t surprise anyone that I think it’s a valuable anger-reduction strategy.
The most important thing about forgiveness is that it helps you stop ruminating. Continuing to think about the provocation, or ruminating, is a big part of what makes anger so problematic for some people. Forgiving the person who has wronged you is an important step toward letting go of those angry thoughts.