Mac tips are plentiful around the internet, and as far as I’m concerned, I can’t get enough. The folks over at CreativeTechs.com have a great tips blog dedicated to Mac, Adobe and photography tips in particular.
They also offer classes and seminars in all of the major Adobe products: Photoshop, Dreamweaver, Lightroom, etc. in the Seattle area. Anyone from around the world can join in, though, and portions of each class are posted after a live event.