its jillian michaels DVD (personal trainer from the US Biggest Loser tv programme). It's FAB. Three levels, each 20 mins long (25 mins including warm up and cool down), and each 20 mins has 3 mins strength, 2 minutes cardio and 1 min abs, repeated 3 times with different exercises. All you need are hand weights and the DVD.
I've done it every day for the last 12 days, and my abs are noticably more defined and I am much stronger than when I started.