As you know the triceps forms around 2/3 of your upper arm so it needs some serious work. And to be honest the motherfucker can take a lot of punishment. The following exercise is called TRICEPS DEATH and can be used as great finisher of your triceps workout. You can also use it in your main workout.
As you know the last 1/3 (lockout) of a bench press is pure triceps strength. Also the narrower your grip on the bench press and the closer are your elbows to the sides the more triceps dominant the movement. TRICEPS DEATH takes those two in consideration and offers a brutal triceps exercise.
Follow these steps for performing the TRICEPS DEATH.
Note: You will need a training partner for performing this exercise.
1) Assume your usual position for close grip bench presses. If you've never done a close grip bench press before practice those just to get used to the movement.
2) Have a training partner put a powerlifting board on your chest. Most people start from a higher box - usually 3-board and work there way to a smaller one.
Note: Powerlifting board is not some special equipement you need to pay USD 1000 for. It's just a stack of regular wooden boards with handles. You can make it yourself. The below picture shows a 3-board.
3) Perform a few reps and have a training partner put a smaller board on your chest.
4) Perform step 3 until you reach the smallest 1-board you have. By that time your triceps will be hurting units.
Watch the following video for complete demonstration.