http://www.atmel.com/Images/doc0856.pdf is probably what you want.
Each chip datasheet has an "instruction set summary", but they fail to go into enough detail for anyone to start writing assembler code. The "AVR Instruction set" document linked above describes the union of all existing AVR chips, and not all of them implement all of the instructions described in the document.
complete opcodes map
A "map" doesn't work too well, because the instructions are 16bits, and don't always divide nicely into opcode/src/dst fields.
However, there is this attempt: avr-instructionset-print.pdf - Google Drive
http://avrfreaks.net is a better site to discuss AVR assembly language. There are (many) tutorials there as well.