I basically go to bed early if I can, charge up the phone, and turn it on after about 3-4 AM, when I go to the bathroom, and then I jerk awake at regular intervals to check the time. Hasn't failed me so far, though I don't like to do it this way. There are many times when I simply can't have a vibrating clock because I'm in primitive camping, and I have to be at work in the faire early in the morning.
