Killer Fitness App

Recently I have been thinking I wanted to have a fitness routine I could do at home, that was either a CD or an iPad, iPhone app.  I've found that while I tend to be  self directed, I'm not motivated enough to do an intense get me sweating type workout on my own.  One of my patients (thanks Ilana) mentioned that she was re-enthused about exercise because of an iPhone app.  Well I tried it yesterday and judging by how much I sweated and how my muscles feel this morning it worked.  What is the app and how much is it you say?  It's "Nike Training Club" and it's free!