The 20 hacks in Chapter 1 (Configuration Hacks) deal from the selectors matching SD card on the intricacies of overclocking, the headless use, installation of a reset button and mobility.
In Chapter 2 (Hacking Linux for the Raspberry Pi) concerns ia building your own kernel, update the firmware, the alternative distribution occidentalis and Android on the Raspberry.
Samba, print server, the phone software Asteriks and installing the Apache web server are priorities of Chapter 3 (Raspberry Pi Around the House).
In the 4th chapter (hacking the Outdoors) It's not just about mandatory interrogation of sensors (temperature, light humidity, GPS) but also to find ways to protect the Raspi against water.
Multimedia Hacks (Chapter 5) provides - as the name suggests - some interesting hacks to play video files, install additional video codecs, the construction of a jukebox and control via touchscreen. When Raspberry as Media Center XBMC is used. Photographers could hack the remote control of a DSLR like gPhoto means, as is the construction of a photobooth eg for use at events.
In the final chapter (Extend your Pi) will be shown how to control the GPIOs through a Web browser. Interesting also the slightly longer Hack 58 via dena circuit / connection of Arduino Shields. Other categories: control of a 3D printer, connect a numeric keypad (Hack 58), build a simple MIDI controller "supercomputer" on the basis of several Raspi.
Completed this is completely successful book from the 20-page index.
Note: The first two chapters are devoted to more basics, see the following sections and advanced one way or another suggestion for your next project. In addition to the standard "operating system" Raspian be in a variety of hacks and any special features of alternative distribution Pidora, a Fedora Remix for Raspi represented.
Definitely worth reading.