In Mac OS X Mountain Lion, you can tie your actual Apple ID to your OS X user account fairly easily. In most cases, this will be your iCloud account. There are many good reasons to do this, but this biggest is that if you ever forget your desktop login password, you can reset it via your Apple ID leaving no need to use recovery mode to reset it.
Not sure how? Follow along and we'll show you.
That's it. Your Apple ID is now tied to your Mac user account. This means if you were to ever forget your desktop password, you can use your Apple ID to reset it. Just make sure the Allow user to reset password using Apple ID option box is checked like shown in the photo below.