When I was a kid, my Mom didn't plan her menus. We went to the grocery stores every Friday and wandered around trying to decide what we needed for the week. Mom also had to get stuff for in my Dad's lunch box to take to work at GM. She then spent the rest of the week trying to decide what to thaw and make that evening.
Fast forward to 2010. I only shop every two weeks and try to use our limited grocery budget to the best of my abilities. I hate not knowing what to make and I don't like trying to thaw things quickly. So I menu plan. I save money and gas by shopping every two weeks. I always know the night before what needs taken out of the freezer and how to plan the next day, eg, throw supper in the crock pot after supper or cook just before eating. I don't follow my menu plans to the letter, some weeks it is more like a guide. Sometimes life gets in the way and I have to re-vamp everything (like when Colin has emergency surgery, that menu went right out the window).
Previously, I've just written the menus on paper. But this year I got a new white board for phone messages. I found this one at Staples. It has spaces for the phone and for paper messages (we don't use paper much), but the new and exciting part was the month calendar (I know I'm an office supply geek). I'm able to actually write the menus on the day they are scheduled and I write down any events that come up for those days. This way it's easy to see if any meals need shifted, easy meals moved to a busy day, etc. It also helps keep life more organized. My real calendar is across the kitchen on the back door and not always visible from the phone (which is attached to the wall).
Now all I have to do is figure out a way to put all my recipes (titles not actual recipes) on the computer so I can, maybe, automate the process a little bit. Some weeks it takes me longer than others to make my menus. I also have a list (well a number of pages) of recipe ideas that I want to try. That way I don't have to pull out my cookbooks just to make plans. I can just go down my list and see what tickles my fancy.
I can't do without my menu plans. I'd be lost and we wouldn't eat as well as we do now.