Forget about setting a password on your Mac as a way to protect your data. It seems MacOS X passwords are extremely easily hacked simply by booting a Mac into single user mode.
When starting the Mac, after the chime, hold the Apple and S keys – This will enter the OS into single user mode.
To crack a the machines password you will need to know the username of main account. If you don’t know the username, while in single user mode, type:
niutil -list . /users
After the username is obtained then type in:
Be sure to replace username with the username of the machine. Even though this hack will grant you entry to the Mac, all the keychain passwords on the compromised machine will be erased.
Thanks for the tip Adam! (Also, Couldn’t resist the reference in the title)