Embedded C programming material
For C programming - embedded or otherwise, you need The C Programming Language by Brian Kernighan and Dennis Ritchie, popularly known as K&amp;R.



I have one book on PICs, I like it: The Quintessential PIC® Microcontroller by Sid Katzen.



For the BeagleBoard, some background in embedded Linux will be important. Here's a good book written by a good friend: Building Embedded Linux Systems by Karim Yaghmour, Jon Masters, Gilad Ben-Yossef and Philippe Gerum.