No mine never got beyond the hand written paper on a clip board stage- and then it was ripped into several pieces by my lovelies for no apparent reason. So if you want to be simple and do it that way, laminate your pages and use a dry erase marker to keep track of what you have! Since I've been such a slacker I went and found some websites with systems for you to borrow:
Prepared LDS Family has inventory pages that you print and put into a binder system- may I suggest putting the pages in sheet protectors if you have destructive munchkins. (like me) The whole site is filled with excellent information on gathering and rotating a 3-12 month food supply. I think this would be especially good if you have food stashed around your house, the binder would be a great central location to list what you have and where so you aren't running around looking in closets and under beds for things.
Track My Food Storage.com actually allows you to set up an account and manage your food storage online, could be helpful!
One of my neighbors has a good system, they have a large poster hanging on the back of their pantry door with little library card style pockets all over it labeled with the necessities (flour, sugar, beans, wheat, rice etc) and then small cards representing how many cans they have tucked into each one- so 20 cards in the sugar pocket for 20 cans of sugar, etc and when they pull out a new can, they also pull a card and put it into a large pocket at the top, so they can easily see what they need to replace- very smart idea, I think I could do that for my cannery type items.
Another idea is using index cards in a box to keep track, for more on that idea click HERE.
Once you know what you have, it shouldn't be too hard to type it up and put it into some kind of a spread sheet that you can print and update by hand, or just save it on your computer and update weekly or something, either way, it's a smart thing to do to avoid wasting food or running out of important ingredients!
A great article to help you if you're just starting to gather your food storage can be found HERE.
And if you need something to scare you a little, check out this website- the US Debt Clock. Those numbers are climbing by the minute with no end in sight.