Android/iOS: For most of us, a shopping list is a last second list put together on a whim. Capitan is an app that takes a different approach, syncing lists with family members, alerting them when you're at the store, and remembering what you usually buy.
On the surface, Capitan is a pretty simple syncing grocery list (that works fine as just that). Once you have it set up, you and your family can easily make a grocery list, special event shopping lists, or whatever else. When you (or someone else) is at the store, everyone else gets a notification so they can quickly add any last minute items. What's more interesting is how Capitan learns your habits over time. It pays attention to what you usually buy and lets you know when you might be running low on something. As these things tend to go, your mileage may vary on how well Capitan does with its predictions, but it's worth a look for its syncing capabilities alone.