I weigh myself every morning. I've read a bunch of posts, by many different authors, recommending against this practice. The main argument against it is that your weight fluctuates so much day-to-day that a daily measurement isn't accurate; that if you try to figure out why your weight goes up or down you'll just frustrate yourself.
The thing is, you have to accept that argument. Acknowledge it. I weight myself every morning and don't pretend to know why my weight goes up or down. Instead, I use it to reinforce habits.
Did my weight go up? There's a lot of reasons that could happen, but if I ate some potatoes the day before I'll blame it on the potatoes. Or not workout out enough, or not running farther. Did my weight go down? I use that to cheer myself on, to remind myself to stick to eating good foods and exercising.
The key is to make an emotional association between what you see on the scale and a behavior. Losing a pound is a great feeling, that's what I want -- and I try to transfer some of that feel-good to habits that I want to reinforce. It's important to not pretend that I know something, that "obviously I gained weight because I ate some berries with dinner", or whatever. I keep records so that I know where my weight is going, but I could do that just by weighing myself once a week.
There's another benefit to frequent measurements, and that's to get an idea of where my weight really is. If I just weigh once a week, then I have a very rough picture of where my weight is. Each weekly reading would be within a pound or two of my 'true' weight, but with weight loss going on as it is, I wouldn't know whether that week's reading was high or low. By measuring myself every day, I have a bunch more data points and so a clearer picture of what my weight is actually doing.
I will continue to weigh myself every day. Daily measurements are a great tool for motivating myself, to reinforce good habits and to break bad habits.