Are you talking about an app like Gyft.co or e-gifter?
They sell gift cards for Bitcoins.. Especially with Gyft, you can load them with Gyft points and eventually you can choose what gift card you want when the time comes.. However its in the US only (Gyft)
I use e-gifter and Gyft. They are a great first step. You find a restaurant (or shop) on there that you want to go to then you go to that place and buy a gift card for close to the amount you are going to spend. Then you make the purchase and usually have a few dollars left over.
I was thinking of something that hides all of those steps for the user. You pull up a map, see all of the places nearby that accept Bitcoin (like coinmap) but it includes all of the included gift card places as well.
You walk into the shop and the app detects your location. You get up to the cashier and just pull out your app, you click "Pay" and a barcode pops up. You pay and your bitcoin balance reflects the amount you spent.
Example:
e-gifter & Gyft now:
I want to shop at Walmart. I check to see which one has a Walmart gift card. I see that Gyft provides that card (not e-gifter, and I have to purchase Gyft points to put toward Walmart's card).
Say I have a $17 purchase.
I pay for a $25 gift card.
I send my bitcoins.
I wait for the transaction to go through.
I get a $25 gift card.
I pull open my Wallet on the app and choose my Walmart gift card.
I pay the cashier with the barcode.
Hot Wallet app:
I want to buy some food. I open the app's map and see that there's a Walmart nearby that accepts bitcoin (as well as Whole Foods and maybe a local shop).
I have a $17 purchase.
I go to the cashier and open my payment app.
The app shows a bar code and the cashier scans it.
$17 payment received by Walmart, $17 is deducted from my Hot Wallet bitcoin balance.
If it was a local shop accepting bitcoin directly the step would just be scanning a QR code instead of popping up a bar code.