I created mine by just standing in front of my pantry and writing things down. Ditto the baking/spice cabinets. I then walked through the store with the list one day and jotted down things as I got to them. I have three sections. One for the regular grocery store, one for Trader Joe's (about 45 miles away), and one for Costco. I can print a list and go through the cabinets and my menus and check for overlap. I've seen lists available on sites like Better Homes and Gardens (bhg.com) or orgainzedhome.com (I think that's it) but so often there's gobs of stuff I don't want and the lists are edit-able.
Oh, one other thing, if you've got the time (HA!) is to take a look at allrecipes.com. I'd guess other sites have similar features but I've only explored allrecipes. If you create an account, you can create and save shopping lists. You can click on "add to shopping list" when you find a recipe you want to make. It looks like it could really be useful but you'd have to take a few to set some things up and have a computer handy when you're working on meal planning/grocery list making.