Pretty much any *NIX (that doesn't have hard drive encryption):
Boot an OS-on-a-disc chroot passwd root
The OS X install disc happens to make it pretty, but it's not a challenge. You can't do the same from a Windows Install disc, but any number of boot discs will let you change Windows passwords as well.
With OS X (at least up to 10.3, haven't tried it since) there's a certain file you can delete and then reboot and it will give you the ability to set the root password so target disc mode is another easy way in.
Physical access + non-encrypted hard drive = rootable.
no subject
Boot an OS-on-a-disc
chroot
passwd root
The OS X install disc happens to make it pretty, but it's not a challenge. You can't do the same from a Windows Install disc, but any number of boot discs will let you change Windows passwords as well.
With OS X (at least up to 10.3, haven't tried it since) there's a certain file you can delete and then reboot and it will give you the ability to set the root password so target disc mode is another easy way in.
Physical access + non-encrypted hard drive = rootable.