Photoshop isn’t exactly a "motion" app, but for me, at least, it’s a pretty essential tool. Sitepoint has a book on Photoshop that’s Web-centric but has some handy quick tips for visual design (especially since we’re often working at resolutions similar to Web projects, and building Processing assets and the like), free for download:
You just have to provide an email address. I didn’t look too closely, so we’ll see if I now get a whole bunch of Sitepoint spam.
Of course, speaking as an author, buying books is good, too, so if you’ve finished any great reads lately related to CDMo, let us know!