- In & Outs (25 reps). Sit on the floor with your knees bent and feet off the ground. Raise your arms straight overhead. Bring your knees in towards your chest. Straighten your legs back out and repeat movement.
- Seated Bicycles (25 reps forward, 25 reps backward). Starting in the same position as In & Out, pedal your feet as if you were riding a bike, and keep them from touching the floor. Each revolution counts as one rep.
- Seated Crunchy Frogs (25 reps). Similar to In & Outs, but start with your hands stretched out to the sides and parallel to the floor. Each time your knees come in towards your chest, bring your arms in around your knees.
- Crossed Leg / Wide Leg Sit-Ups (25 reps). Lie down with your feet crossed or legs wide. Place a hand behind your head and bring your torso up to perform a standard sit-up, but reach the other arm out to touch the opposite foot. Alternate arms for each rep.
- Fifer Scissors (25 reps). Lie down. Extend one leg up towards the ceiling and keep the other leg a few inches off the floor. Both legs must stay straight, with both feet flexed. Alternate legs in a scissor motion with a 3-count hold for each rep.
- Hip Rock & Raise (25 reps). While on your back, bend your legs so that the bottoms of both feet are touching. Push your hips and pelvis up, driving your feet up towards the ceiling at a 90 degree angle to your body. Legs should not touch the ground during this exercise.
- Pulse-Ups (25 reps). Same as Hip Rock & Raise, but keep your legs straight and feet flexed when driving up towards the ceiling.
- Roll-Up / V-Ups (25 reps). Lie down with your legs straight out and arms extended straight towards the ceiling. Do a standard sit-up from this position, touching your toes with your hands. On the way back down, raise your legs up off the ground at a 45 degree angle, and do another sit-up while keeping your legs in the air. Repeat.
- Oblique V-Ups (25 reps on each side). Lie on your side with your legs at a 30-degree angle and your "top" arm bent, resting your hand behind your head. Lift up your legs and torso at the same time, driving your bent elbow towards your lifted leg. Legs and shoulders must stay off the floor once you begin.
- Leg Climbs (25 reps). Lie down with one leg bent (foot on floor) and the other leg extended straight out at a 45 degree angle. "Climb" your straight leg with alternating hands. Repeat on the other side.
- Mason Twists (40 reps). Starting in the seated In & Out position, clasp your hands together, keeping your feet off the floor at all times. Twist your upper torso from side to side, touching the floor on either side of your butt using your knuckles.
[UPDATE: Someone who evidently doesn't give a rat's ass about copyright infringement has posted the entire Ab Ripper X workout on Vimeo here. Check it out if you're interested in seeing what Ab Ripper X is all about, but then go buy the real thing.]