Twitch Caster is a fully fledged Twitch.tv search app that you can cast to your Chromecast. Future versions will allow casting to multiple platforms (Roku, webOS, Amazon and LG tv's). Currently this is v1.0. There are a couple of bugs and Is not perfect, however I have put it up as it is usable.
✔ Search for Games, Channels and Streams✔ Cast to Chromecast✔ Volume Control✔ Add your favorite casters for quick access