Pattern making tutorial

I would really like to learn how to design my own sewing patterns (clothing that is) but don't have a clue how. Anyone know of any books or websites that tell you how?

Here is a great one: http://www.amazon.com/Make-Sewing-Patterns-Donald-McCunn/dp/0932538002

Also there are several newer sewing books which help you draw up your own patterns and how to modify others:
Sew What! Skirts
Sew U

Both are great books. 

I own this book: http://www.amazon.com/Make-Your-Own-Dress-Patterns/dp/0486452549/ref=sr_1_1?ie=UTF8&qid=1248701893&sr=8-1 which, despite the title, shows you how to make patterns for just about everything (not just dresses!).  The author also hosts a yahoo group so if you're stuck or have questions you can get some help.  (I do have to admit that I haven't actually used the book yet, so I can't tell you how good it is, but it came highly reccomended).