Build Your Own Electronics Workshop is a great resource for anyone interested in electronics.
Electronic Circuits for the Evil Genius is a complete electronics course in just 225 pages.
CNC Robotics is a step-by-step guide to building your own CNC machine. It is an excellent starting point for anyone who is thinking about building a CNC system of any type.
123 PIC Microcontroller Experiments for the Evil Genius is a excellent starting resource for anyone interested in the PIC Microcontroller.
Easy Microcontrol'n is a great beginners books for PICmicro users.