Store Companion is a new app available for Windows Phone owners that provides the ability to sift through the apps available for Windows 8 devices. So, while you're sitting in the department store, waiting for your spouse to complete the Christmas shopping, you can locate new apps to install on your Microsoft Surface once you get back home.
The interface models pretty closely to what you're used to using when working with the Windows Phone store app on the smartphone. You can search, view app details such as ratings and screenshots, and then use the sharing function to send the app's link to a friend or out to a social network.
As a tip, if you locate something you want to install on your own device, use the Windows Phone sharing function to send yourself an email containing the link. That way, when you finally sit down with your Windows 8 device you can just click or tap the link and be whisked away to the Windows Store location to install the new-found goodie.
Here's the link to the app in the Windows Phone store: Store Companion