A Better Grocery List

I’d like to get more into mobile development and what better way than to just do it.  I was trying to figure out a decent idea that in the end could actually end up in an app store.  A game would be great but I don’t have the graphic design skill to pull that off at all.  I thought about the last time I tried to use an iPhone grocery list and it wasn’t ideal.  So how would I try to improve it?  Here are the main features I was thinking about:

• Allow sharing and contributions from any device.  The wife should be able to think of something and have it end up on my list and vice versa.  It’s worthless if we have to keep the usual list on the refrigerator and dump it into our phones.  This to me would be a huge improvement.
• Sort and show items by store section.  Right now I write down a number indicating the section: 1-Fresh, 2-Refrigerated, 3-Main, 4-Deli, etc.  I want to easily swipe between store sections showing only those items while I walk from section to section.
• Allow entering of quantity.  It has to be flexible enough to recognize quickly written units.  I should be able to enter “1 gallon of Milk” and end up with it understanding “Milk, 1 gallon.”  No drop down lists or selectors, those take way too long.
• Doesn’t have to be limited to grocery lists…

What would it look like?  Here’s something I drew up pretty quickly.  It shows the last two features at least.

What about sharing lists?  It has to be really easy.  No email, no exiting the application.  I have to be able to tell my wife in 10 seconds or so how to get it if she’s already in the store.  This will require it be backed by a web app or at least a database, kinda like instagr.am which you can’t really use on the web directly.  I ended up thinking I could tell her an identifier over the phone or send her a link (can you link directly into an app?).