(Become an Xcoder book).
I wish I had this when I was learning programming for the first time in high school(well, my teacher was great, but writing commandline tools gets boring after a little while)
This book covers everything from the utter basics to Cocoa Graphical User Interface(GUI) development.
Using Automator lets you well, automate tasks, without programming. A great video/introduction is from the Applescrip/Automator guru Sal Soghoian at Google Video (here)