Now that the Chromecast development kit has been out for over a month, more and more Android apps are being released or updated to work with the Chromecast.
Everything from games to streaming local content to personalized news stations is available. Unfortunately, there is no dedicated Chromecast section on Google Play that makes these new or updated apps easy to find. You can do a basic search for "chromecast", but quite a few devs have "chromecast" tags on their apps, whether they have support for it or not.
There's also the Chromecast page, but c'mon, have you seen it lately?!? It doesn't even begin to scratch the surface of the multitude of third-party apps available.
Just as the name implies, the app curates Google Play apps that offer Chromecast support, with the ability to have anyone offer app suggestions to keep the list as updated as possible.
On first opening, the app will display a list of recent app and Chromecast news. Hit the hamburger menu button on the top left to choose specific sections. The settings panel is fairly bare at the moment, with one simple option to choose the section you want displayed when opening the app.
Cast Store starts you with two categories; Apps and Games. Within each are various sub-categories, which I found to be extremely helpful in tracking down apps for specific purposes.
Tapping on the red number of the top right will take you the the "Recently Added" section, tapping the app name will take you to its Google Play page, and tapping the star icon next to the app's name will place it in your "My favorites" section.
You can think of Cast Store for Chromecast as a much better alternative to Google Play for finding apps meant specifically for our Chromecasts. The UI may not be the prettiest, but it gets the job done...take note Google!