Try this for a multi-angled attack on your abs. Rollouts are one of the best exercises for activating your entire midsection, but this variation will make them even more effective.
Lateral-Resisted Ab Wheel Rollout
Attach a band to something stable coming from the side a few feet in front of you. Then loop it around your hand. The band should form about a 90-degree angle with your body when you're fully rolled out.
The band adds a lateral component to resist it from pulling you sideways. On the way back, there's also an added resistance, increasing as the wheel returns under your shoulders.
Traditionally, rollouts are an "anti-extension" exercise where your abs are resisting spinal extension and an anterior tilt of your pelvis. The band adds an "anti-lateral-flexion" component at the bottom. It also loads your spinal flexion as you stretch the band toward you.