In Doreen's book Healing with the Angels there is an entire section dedicated to Number Sequences from the Angels. Quote: "We can't write our messages to you in the sky. You've got to pay attention and believe when you see any patterns forming in your life---especially in response to any questions or prayers that you've posed. When you hear the same song repeatedly or see the same number sequence, who do you think is behind this? Your angels, of course!"
444's: The angels are surrounding you now, reassuring you of their love and help. Don't worry because an Angel's help is nearby.
666's: Your thoughts are out of balance right now, focused too much on the material world. This number sequence asks you to balance your thoughts between heaven and earth Life the famous "Sermon on the Mount", the angels ask you to focus on spirit and service, and know that your material and emotional needs will automatically be met as a result.
There's also info on the web regarding these number sequences.