We have seen more than a few Google Glass apps at this point. The use cases appear to vary widely and we have seen everything from using them in surgery to controlling your home thermostat. That being said, it looks like this latest is a bit more practical for everyday use. This one is called Crystal Shopper and has recently been shown as part of the Breaking Glass Glassware hackathon.
This one is fairly simple and something that we have seen with smartphone apps. The Crystal Shopper app will allow users to scan barcodes and get details on pricing and ratings. The app is currently pulling data from Amazon and the cards will show details to include the item name and picture along with the lowest and highest prices and the rating.
Using the app appears simple enough -- launch the card for the app and proceed to scan the barcode on the item you are holding. This has the obvious price check ability for when you are out and about in a store, but it could also be useful just about anywhere. Say for example, when you find a book (or other item) at a friends house. Using the Crystal Shopper app you could scan the item, check for price and more.
That and more is where the use case expands. Aside from using the app for immediate price checks, it can also be used to save these items for later. As you will see in the demo video, there are a few head gestures available. A nod front and back will add the item to your list and a shake side to side will discard that item with a "not today" listing.
Those with Google Glass can download the Crystal Shopper app as of today. The app can be found by navigating here; https://crystalshopper.herokuapp.com/.