On the cooking side of things, I found I was spending a lot of money buying lunches. Sydney is a VERY expensive city: a 'cheap' lunch in the CBD costs at least $7. So, we're talking about saving at least $35-50 per week. Over a year, that's approx $1500-2000 per year. And often, it's not as good as things I like to make for myself.
So I cook double-or-triple the quantities of recipes on the weekends... I take pride in making complex curries, slow-cooked casseroles and the like. Usually, doubling or tripling the quantities does not change the cooking time significantly and there are economies of scale with the costs as well.
Then, I package up the extra into lunch and dinner-sized portions for myself, wife and family for the week in the freezer.
This way, we all get cheap lunches (cost approx $1-2) and gain extra time at dinner during the weekdays (no cooking! just re-heat and add rice/salad/veges).
I'd say that as well as saving $1500-2000 per year, it's also saved us an hour or 3 every single week. Frankly, it's worth it if just for the time saved.