Does the Windows Store have an API?
For example, when you open the "store" application, there is a "top free" list that displays the 100 most popular free applications. A list coming from an HTTP endpoint somewhere on the Internet?
There is no official API for accessing content in the Windows Store. I am sure that the content is being pulled from the Internet through an HTTP or HTTPS endpoint, but using an undocumented service like this is most likely not recommended. It also doesn't look like there is a protocol activation scheme registered to run the store. The closest I can find is MarketplaceDetailTask on Windows Phone. http://msdn.microsoft.com/en-us/library/windowsphone/develop/microsoft.phone.tasks.marketplacedetailtask(v=vs.105).aspx
The only other supported way to launch the store will be to use links to applications that make the store open.