Many of the most famous studies in Social Psychology involve cognitive dissonance: the Standford Prison Experiment, the Asch conformity study, and Milgrim's obedience study, to name a few.
But public life is also riddled with examples of politicians, celebreties, and plain folks like ourselves engaging in this self-justification, sometimes with dire consequences. My favorite book on the subject, by authors Elliot Aronson and Carol Tarvis, is called Mistakes Were Made, But Not By Me (2007). It illuminates the prevalence of this behavior using examples from recent events.
Another great resource for those interested in all aspects of social psychology is the Social Psychology Network. It has TONS (over 17,000!) links to all types of information and organizations related to social psych. Happy surfing!