radare can do commandline binary file disassembly.
rasm2 -a 6502 -D -B -o starting-address -f filename
Lowercase -d to get just the instructions.
Another nice project, I had actually encountered it previously while searching for tools for a rather quirky 6502 variant that ultimately I'm going to have to write my own tools for. Coding up some small 6502 related tools makes for a good practice run before I tackle the hairy beast (m7900).
