AVR Related Resources

Here are some useful documents because atmel.com site doesn't not exist any more...

Arduino Various topics about Arduino
ATmega328p Datasheet Basic of all
8-bit AVR Instruction Set For assembler writers the instructions set
AVR Assembler How to write in assembler language
Family with ATmega2560 datasheet  
GCC Inline Assembler Cookbook Excellent site about how to replace C++ routines by assembler, especially port manipulation