Here's a workout we did last month for bootcamp that is a great way to trim & tone the midsection for summer. This is a 45-15 interval circuit workout. Perform each movement for 45 seconds with a 15 second rest in between each move. The entire circuit lasts 5:00. Rest for 30 seconds (unless you dying and make it a minute!) and then move to the next circuit. These can really be done anywhere, although i'm not sure how well the shuttle runs will be in your kitchen!
For best results perform each circuit twice for a 20:00 workout.