If your getting started with your Raspberry Pi you should checkout the Kindle edition of Meet the Raspberry Pi
The Kindle edition only cost £3.29 from Amazon and makes a great getting started guide, including mastering Linux, getting started and with the GPIO ports and working with the GPIO ports.
Seems like a good deal to me.
The essential preview guide to getting started with Raspberry Pi ® computing and programming
Originally conceived of as a fun, easy way for kids (and curious adults) to learn computer programming, the Raspberry Pi quickly evolved into a remarkably robust, credit-card-size computer that can be used for everything from playing HD videos and hacking around with hardware to learning to program!
Co-authored by one of the creators of the Raspberry Pi, this special preview eBook fills you in on everything you need to know to get up and running on your Raspberry Pi in no time, including how to:
• Connect to a keyboard, mouse, monitor and other peripherals
• Install software
• Master basic Linux system administration
• Configure your Raspberry Pi
• Connect to wired or wireless networks
• Diagnose and troubleshoot common problems
• Use the GPIO port to flash an LED or read a button
Meet the Raspberry Pi provides a sneak peek preview of how to make the most out of the world’s first truly compact computer.