Atmel Studio (Atmel’s free IDE) http://www.atmel.com/atmelstudio
JTAGICEmkII (On-chip programming and debugging tool) http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3353
AVR ONE! (On-chip programming and debugging tool) http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4279