Shaun T's and his Insanity workout was featured on ABC news. Hands down this is one of my favorite cardio workouts on the market. When I am not doing my customized circuits I grab one of my Insanity DVDs to get a mega workout in.
Check out the video when you have time:
http://abcnews.go.com/Health/video/shaun-insanity-fitness-workout-routine-build-muscle-lose-weight-12089954