If you are looking for something to do while at home I would seriously consider Yoga. It is a lot tougher to keep motivated doing it at home alone as opposed to doing it in a class, as well as harder to learn the poses, but it will seriously tone you up and restore the flexibility we all lose over the years. Just do a search on Amazon for different Yoga dvd's, although the Yoga page on About.com
http://yoga.about.com/index.htm?terms=yoga is a hell of a resource to start out with if you want to learn about the various types of Yoga. I took a Yoga class 14 years ago in college and was amazed what a workout it is, and I take one at my gym when I can fit it in.