One of the basic things about the Hackers Diet is that daily weight is meaningless - it can vary by as much as 4 -+ pounds a day, based on how much you eat, how much you drink, how much salt you took in, et al. What is VERY meaningful is weight over time, reflected in a moving average. So, over a 2 week period my weight might be all over the place (and may look like I'm gaining), but as long as the trend line is negative, then I'm loosing weight. The above is my chart for the last two years. The blue is daily weight, and the red is the trend line. You can see the HUGE weight loss in that initial part, and then a slow upward trend, with a bunch of flat-lines, losses, and gains, over about 1.5 years.
Using this info, you can also figure out things like how much you are burning every day (Look at average daily intake vs avg pounds per week. 500 cals deficit = 1 pound of weight loss or gain per week). This lets me nail down exactly what I need to do to loose X pounds a week. Handy!
I will also be using this for the start of 2006, to keep VERY close track of my pounds per week loss/gain - Using the tools with the Hackers Diet, I will adjust my cals per day to hit my target weekly loss.