One of the biggest issues my wife and I have is remembering what to get at the grocery store. We've tried shared spreadsheets, various list applications, and jotting stuff down on paper. Nothing sticks. We either forget to do it or just don't want to deal with hassle (thus is the case with most apps). Bring! may change that. Hopefully, anyway.
Basically, it's a super simple, and seemingly intuitive shopping list app.