I've shed about 10kg of excess weight and have dropped out of the 'overweight' category. It has taken a bit over three months, I think.
Wii Fit has been a great help in that it lets me easily track my weight from day to day. I never really got into doing exercise on it, but I always take the daily test. And it's a good back-up option for when I want to work out a bit, and the weather is foul.
I also write down everything I eat, and if I have enough data available, calculate the number of calories that gives me. This in turn has given me a better idea of how many calories should be in a meal or a snack.
It's a bit annoying to weigh out every item I eat, and I often don't bother doing that for things that aren't particularly calorie-dense.
My main snack is nuts; these I weigh out in small portions, because nuts are full of calories - mostly fat. My old, calorie-ignorant self could easily take in 700 calories just by snacking on nuts. Portion control has been the key to my success.