My wife and I use this app for grocery and other various shopping lists. It allows us to add things when we think of them, regardless where we may be. My only complaint is that it runs very slow and it may take awhile for our lists to sync. But overall a helpful, free app.
Update: 9/22/14
I just updated this app yesterday and now its become completely useless. Today the sync button is finally visible and appears to work. However the buttons used to access the catagories (such as lists and calendar) do not respond at all. I emailed the developer so well see what happens.
Agent Nix about Organizer To-Do: Daily Planner, v3.4