I've started tracking my sleep using an app called Sleep Cycle. The way it works is by utilizing the motion detecting in my iPod to track movements during sleep and then estimates how deeply I was sleeping. While I would love to use a Zeo (which tracks brain activity), the Sleep Cycle app dose have some features that I like.
It tracks mood upon waking and other factors like caffeine and exercise that can effect sleep. It also has a built in white noise maker.
My favorite feature is the alarm. You give it an interval during which you want to wake up. It then will pick a moment to ring during that time when you are coming out of a deeper sleep so that it is more of a natural awakening.
Just using once has me really excited to have more gentle mornings.