I've gone back and forth on this issue too. At the moment, I'm decided to weigh every day. I'm thinking of the scale as just another tool in this process, a monitoring tool, if you will. I am enjoying seeing the relationship between what I eat, water, sodium, digestive patterns,etc, and the little fluctuations that reflect them.
I figure if I stay honest with my food choices, and keep tracking, I will see progress over the long term, and FitDay's tools, charts and graphs are a great help. I am really looking forward to seeing what the January graph looks like at the end of this month. Having more than just 4 (weekly) data points on the chart will be good information, I think.