Motion at Wikipedia: A general overview of Motion's history, market position, features, how it works, and references. Check it out and improve it!

Pro Apps Tips: Tips for Motion and Apple's other Pro Apps (Final Cut Pro, DVD Studio Pro, Soundtrack Pro, Logic, Shake, Aperture).

Barefeats: THE resource for speed tests on Mac-related hardware, including graphics cards for Motion and other good technical data.

MotionSmarts: Great Motion-only site run with all content created by the enigmatic Special Case, who can be found often helping folks out on Apple's Motion forum.

Ripple Training: Run by Apple instructor Steve Martin, a great resource for training on all of Apple's Pro Apps. Free tips and inexpensive tutorials for download and on DVD.

dvcreators.net has all kinds of great info about Motion as well as production and post production in general.

Motion in French: a french website dedicated to Motion.

Embryo: a UK site with some cool Motion tutorials