I was going to the grocery store yesterday, and I finally got my chance to try out the gizmo as a shopping list. I don't have any grocery-list software installed, nor have I written any (although that's near the top of my list of Stupid Apps to Learn GUIs by), but there is a perfectly decent to-do program as part of the GPE suite.
So create a category called Groceries. Make each thing to buy a separate item. Display only that category. Show only uncompleted items, and check off each thing as done when you put it in the cart (a bit hard with C right there, but no harder than holding onto a paper list). Cooler yet: completed to-do items don't go away unless you delete them, so after a few trips I should have all the items we usually buy entered. I'll just need to tick the right ones back to uncompleted, and Zam!
Yeah, I am such a loser.