The best online source is: http://www.deansdirectortutorials.com/
There are two useful books, though they are out of print: Advanced Lingo for Games by Gary Rosenzweig and
Real-Time Interactive 3D Games by Allen Partridge.
Lynda.com may also have some courses.
It looks like http://www.deansdirectortutorials.com/ is a good site to learn director. I'm so suprised though, only one decent website that has tutorials. It's almost like learning adobe director is discouraged. Even Adobe doesn't have any official books on their own product, maybe they don't even know how to use it.
It's like the free masons group, in a couple hundred years from now maybe there will be a group called "Free Directors."
On my site, I have a resources page that gives links to every other Director site I know of. Director is not a high profile product in the Adobe family and it has suffered in the lack of marketing and upgrade. For this reason, it has a smaller market and there are less reources (as compared to say Flash) to learning the product. I hope my site is of some value to you.