What sleep charting software exists for Mac OS X? I'm looking for Mac software that will make it easier to generate a chart of my personal sleeping habits. I have a system improvised with Numbers '09, but it doesn't work very well. Is there any software out there that will do this simply? I want to log my sleep/wake times and have the chart generated for a given span of time easily. (If it can project times into the future, that's even better.)
I have this one here, very happy with it. 

http://www.fitbit.com/

The last I checked, you can sign up for a fitbit account and use their web application to manually enter sleep times and get nice graphs and statistics using your web browser to see the data.

I don't think there is an export function and it's clearly not a traditional app where all the data exists on your Mac.