Not loading for me right now. The web really needs the equivalent of an app store. Search engines don't do apps justice. They don't have enough content to index and are often difficult to crawl anyway, being JS-heavy. Chrome Web Store is a good start, but a place with reviews and ratings of browser-independent, no-install, interactive websites would be excellent.
That's a similar direction I'm headed in for http://www.iwaat.com. I think you'll see more sites like http://thetoolbox.cc being created since searching for web apps from google.com is painful. And I can confirm from experience that most web apps have a miniscule amount of content to index, especially compared to blogs and other sites where content-centric sites. However, when you combine a web app's on site content with relevant content from the rest of the web (social media, news, etc), there's enough data to build a halfway decent search engine.
The tough part of your vision is the store. Every web app has their own way of processing payments that would be tough to tie into a single site for an experience similar to Apple's App Store. Chrome Web Store would probably be best positioned to tackle this.