Coach Nicole has a couple of chair workouts posted in the fitness section. www.sparkpeople.com/resource/videos-detail
When you feel you've outgrown those workouts, go to YOUTUBE and search on chair aerobics workouts. You'll find a variety posted for different fitness levels. I've found some of those chair workouts to be quite vigorous. You can also find chair workout DVDs for sale on amazon. But, check your local library first. Your local library is not only a great resource for books, but you can borrow DVDs too.
You might also want to check out Richard Simmons workouts. I remember he had some members doing his workouts while sitting in a chair. that's something that might work for you too.