AVR-Chat

AVR Studio does do a one pass disassembly. Then you have to continuously 
work it with a text editor. Also it doesn't recognize register names, 
memory space and ISR vectors. If the code has a lot of data embedded in 
it then AVR Studio will try to disassemble it into code which makes it 
confusing to to reverse engineer.

The Visual Disassembler is a multi pass disassembler. It allows you to 
specify a device and data areas in the code space. Adding comments and 
data labels is much easier.