What are good waist-cutting work-out exercises?

Any thing that: Gets the heart rate up. Remember if you are trying to "trim" your waist, you are trying to lose weight. For most people, the key component of a weight loss regimen is caloric reduction. So while you shouldn't give up on exercise, first look to optimize(reducing) your caloric intake. Otherwise, when starting out the best exercise are the one's you'll consistently partake in.