Creating a disk image:
http://txfx.net/2012/12/05/raspberry-pi-headless-setup/
$ sudo diskutil unmount /dev/disk1s1
$ sudo dd bs=1M if=/Users/axelav/Downloads/rpi.img of=/dev/rdisk1 # NOTE: `disk1s1` becomes `rdisk1` DONT FUCK THIS UP
$ sudo diskutil eject /dev/rdisk1