"Do not take revenge, my friends, but leave room for God's wrath, for it is written: 'It is mine to avenge; I will repay,' says the Lord." - Romans 12:19
Does it feel good to see someone who has wronged you, or someone you know, get their just rewards? Look at the injustice thrust upon King David of the Bible. Through a series of betrayals, his vain young son, Absalom, took away the throne that rightfully belonged to David. David protested and cried out to God for justice, but recognized that vengeance is a matter for God. It wasn't long before Absalom – who was very proud of his head of flowing hair – had his gorgeous locks caught in a tree as he was riding by. He couldn't untangle himself and died right there. God brought about justice in a rather colorful manner, and although he wept for his son, David was restored to the throne.
God delivers justice in different ways. Sometimes it's through routine personal (and peaceful) interaction. At work, when there is injustice, normal office procedures might result in a just solution. Other times and situations could require the involvement of the police or the courts. And sometimes justice will not be revealed until after our deaths, recognizing that God sees an eternal picture that we cannot comprehend while wrapped up in our temporal, earthly matters.
But do know this: God will bring about justice. Maybe it won't be as dramatic as the culprit getting his hair stuck in a tree. But in the end, God's justice will most certainly be done.