Google has started highlighting applications that support casting content over Chromecast on Google Play recently. The section is visible under Apps << Categories and currently includes just a few apps. At this point only applications like YouTube, Google Play Movies and TV, Google Play Music, Pandora, Netflix, HBO Go and Hulu Plus are listed in the section.
Now that Google has added Chromecast apps as a separate section on Google Play, we can expect to see more entries in the near future.
To remind you, Chromecast is a digital media streamer by Google, which is sold at $35 in the United States. It can share video and audio content from YouTube and other apps/ website mentioned earlier in the post to your HDTV and can also mirror your Chrome browsers tabs.