USEFUL ITEMS
HANDY CHEAT SHEETS
Github Cheat Sheet
Markdown Cheat Sheets (You know you want fancy READMEs.)
WEBSITES
AVR C Tutorial
AVR Tutorial from Lady Ada (founder of Adafruit!)
The Deadlock Empire: Slay Dragons, Master Concurrency!
SOFTWARE
Open On-Chip Debugger (Debugging, in-system programming and boundary-scan testing for embedded target devices)
TEXTBOOKS
The Art of Electronics (HIGHLY recommend)
High Speed Digital Design: A Handbook of Black Magic