Mac OS X Tiger: The Missing Manual. I've never read it, but I hear it recommended often in these forums. Also, the Macs for Dummies book seems to be very well done. I'm not calling you a dummy, I just use that book series when I have trouble understanding something (I used Calculus for Dummies in my Calculus class last year). Hope this helps!!!
I purchased Mac OS X: The Missing Manual as well (based on many recommendations) and it's been fantastic. Combining that with things I've learned from various Mac forums, I got off to a decent start with learning things on my new MBP.
Pogue's Missing Manual gets my vote. Years ago, there was The Llittle Mac Book by Robin Williams and Peachpit Press that might be updated and still around. It would be a lot less expensive than the Missing Manual.