Swiss-ball Incline Triceps Extension
Grab a pair of dumbbells and sit on a Swiss ball. Roll your back down the ball, keeping your stomach tight, until your shoulders are pressed firmly against the ball and your butt is off the ball. Hold the weights with straight arms, angled so the weights are over your forehead. Keeping your upper arms still, bend at the elbows to lower the weights until they're even with the top of your forehead. Pause, then straighten your arms.
Tip: Your triceps comprise more of your arm than your biceps, but you probably work your tri's less. Even the score with some additional tri exercises like dips or close grip bench presses.
Swiss-ball Biceps Curl
Set dumbbells on a bench in front of a wall, or ask someone to hand them to you. Place a Swiss ball against the wall a few feet up from the floor and stand with your lower back against the ball, holding it in place. Hold the dumbbells with palms facing the sides of your thighs. Curl the weights up, rotating your wrists upward so your palms face you by the time the weights reach your shoulders.