I weigh in once per week. I know too much about statistics to think that daily changes on a set of scales will give any kind of accurrate picture of weight loss. There are too many variables such that even your once per week weigh in should be viewed in relation to the general trend of the previous weeks.
And then there;s the question of what do you want to track a loss of? pure weight, in which case your pure weight will fluctuate accoring to how recently you went to the loo and how much fluid you've drunk that day in which case you're probably celebrating/mouring bodily waste in you 1/2 daily weigh ins. FAT loss, however will not be measurable in increments of 1/2 a day. This is actually part of the statistics question (i.e extraneous variable) but many people get caught up on losing "weight" without realising that it's not weight you want to lose but fat.
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"