Any suggestions?

My son has never been aggressive, but now that he's 8, he's REALLY beginning to get that way when he's angry! I have holes in my walls where he's kicked when he's mad, and today I got a call from school saying they had to take him off the bus because he was ticked off and kicking, screaming, etc. The teacher says it is becoming more and more of a problem, and occurs when he doesn't get his way about something. He thinks if he throws a fit, he will get what he wants. How do I make him understand that sometimes the answer is NO! How can I teach him to control his temper? What works for you guys? If I don't curb this now, he's going to be unmanageable as he gets older and stronger! HELP!