The online website for the Windows 8 App Store is still in the "preview" stage and doesn't support searching through for apps. However, if you have a direct link to an app (for example, from the apptivate.ms contest), then you can view its information online, without having to open the Store app.
The problem is, once you're on the webpage, there's no way to actually install the app. No "install" button, no "add to my account" or "download" or anything. The only way (that I've seen) to install the app is to go into the Store app and search for the desired app by name, hunt through the list of results, and install it from there.
Is there any way to just download it directly from the Windows App Store website, or at least open the app in the Store app without having to search for it?